digitalmars.D.announce - dmd 2.029 release

This is a major revision to Phobos, including Andrei's revolutionary new 
range support.

http://www.digitalmars.com/d/2.0/changelog.html
http://ftp.digitalmars.com/dmd.2.029.zip

Apr 20 2009

"Simen Kjaeraas" <simen.kjaras gmail.com> writes:

On Mon, 20 Apr 2009 09:09:09 +0200, Walter Bright <newshound1 digitalmars.com>
wrote:

 This is a major revision to Phobos, including Andrei's revolutionary new  
 range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Butbutbut... I've just barely managed to install 2.028 yet.

Great work! Can't wait to try out the new ranges.

--
Simen

Apr 20 2009

BCS <none anon.com> writes:

Hello Walter,

 This is a major revision to Phobos, including Andrei's revolutionary
 new range support.
 
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Cool template function literals sounds interesting

Apr 20 2009

bearophile <bearophileHUGS lycos.com> writes:

BCS Wrote:
 Cool template function literals sounds interesting


May I have one example of them?
I am looking in the docs, but I am not finding anything...

Bye,
bearophile

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

bearophile wrote:
 BCS Wrote:
 Cool template function literals sounds interesting


 May I have one example of them?
 I am looking in the docs, but I am not finding anything...


void foo(alias f)()
{
     f(3, 4);
}

foo!((x,y){return x * y;))();

Apr 20 2009

bearophile <bearophileHUGS lycos.com> writes:

Walter Bright:
 void foo(alias f)()
 {
      f(3, 4);
 }
 foo!((x,y){return x * y;))();


I have tried:

import std.stdio: writeln;
void foo(alias f)() {
    f(3, 4);
}
void main() {
    foo!( (x, y) { writeln(x * y); } )();
}

And it works, printing 12 :-) Very cute.
This is able to simplify some of the code of (D1) dlibs :-)

I didn't even know that lambda delegates in D2 can now infer the type of their
input argument, so you can use (x, y) instead of (int x, int y). Can you tell
me when this was changed? :-)

Bye,
bearophile

Apr 20 2009

bearophile <bearophileHUGS lycos.com> writes:

In D1 I have written a very hairy (but not too much long) apply() function,
that given a function and some arguments, returns the result of the function
applied to them. (apply() is a basic higher-order thing common in most
functional languages).

So now I'm playing with this new toy of D2, not using it in a serious way yet,
and I have written:

import std.stdio: writeln;
auto apply(alias f, TyArgs...)(TyArgs args) {
    return f(args);
}
void main() {
    writeln(  apply!( (x, y) { return x * y; } )(3, 4)  );
}

But when I compile it the compile spits out at compile-time:
Assertion failure: '0' on line 935 in file 'glue.c'

Bye,
bearophile

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

bearophile wrote:
 In D1 I have written a very hairy (but not too much long) apply() function,
that given a function and some arguments, returns the result of the function
applied to them. (apply() is a basic higher-order thing common in most
functional languages).
 
 So now I'm playing with this new toy of D2, not using it in a serious way yet,
and I have written:
 
 import std.stdio: writeln;
 auto apply(alias f, TyArgs...)(TyArgs args) {
     return f(args);
 }
 void main() {
     writeln(  apply!( (x, y) { return x * y; } )(3, 4)  );
 }
 
 But when I compile it the compile spits out at compile-time:
 Assertion failure: '0' on line 935 in file 'glue.c'
 
 Bye,
 bearophile


Your code should work as expected. (Also, right off the bat, any 
assertion failure in the compiler is a bug.) Could you submit to bugzilla?

Andrei

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

bearophile wrote:
 Assertion failure: '0' on line 935 in file 'glue.c'


All assertion failures are compiler bugs and belong in bugzilla:

http://d.puremagic.com/issues/show_bug.cgi?id=2863

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

bearophile wrote:
 I didn't even know that lambda delegates in D2 can now infer the type
 of their input argument, so you can use (x, y) instead of (int x, int
 y). Can you tell me when this was changed? :-)


That change *is* the template function literals, and they are only valid 
as template arguments.

Apr 20 2009

bearophile <bearophileHUGS lycos.com> writes:

tama:
 void foo(alias f)()
 {
      writefln(f(3, 4));
 }
 foo!((x,y){ return x * y; })();
 
 This code doesn't work(compile error).


To me the following works:

import std.stdio: writeln;
void foo(alias f)() {
     writeln(f(3, 4));
}
void main() {
    foo!((x,y){ return x * y; })();
}

Bye,
bearophile

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

tama wrote:
 I tested following code.
 
 writefln(3 * 4);
 
 This code doesn't work in the first place:-<


Yes, that's one of the breaking changes in the new phobos2. writefln
expects its first argument to be a format string.

If it isn't, use writeln instead.

Apr 20 2009

Russell Lewis <webmaster villagersonline.com> writes:

Walter Bright wrote:
 tama wrote:
 I tested following code.

 writefln(3 * 4);

 This code doesn't work in the first place:-<


 Yes, that's one of the breaking changes in the new phobos2. writefln
 expects its first argument to be a format string.
 
 If it isn't, use writeln instead.


I just hit the same breakage. :(

Since the compiler can detect this situation statically, shouldn't 
Phobos just statically redirect the call to writeln() ?

Apr 19 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Russell Lewis wrote:
 Walter Bright wrote:
 tama wrote:
 I tested following code.

 writefln(3 * 4);

 This code doesn't work in the first place:-<


 Yes, that's one of the breaking changes in the new phobos2. writefln
 expects its first argument to be a format string.

 If it isn't, use writeln instead.


 I just hit the same breakage. :(
 
 Since the compiler can detect this situation statically, shouldn't 
 Phobos just statically redirect the call to writeln() ?


It did for a while. For cleanliness purposes, I thought it was about 
time to eliminate that. Also, extraneous arguments passed to writef will 
be ignored, not printed with default formatting.

Andrei

Apr 20 2009

bearophile <bearophileHUGS lycos.com> writes:

Andrei Alexandrescu:
 extraneous arguments passed to writef will 
 be ignored, not printed with default formatting.


That sounds bad:
=> "Errors should never pass silently."
It's better to raise a compilation error. (And if that's not possible, then an
exception at run-time. But a compilation error is much better).

Bye,
bearophile

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

bearophile wrote:
 Andrei Alexandrescu:
 extraneous arguments passed to writef will be ignored, not printed
 with default formatting.


 That sounds bad: => "Errors should never pass silently." It's better
 to raise a compilation error. (And if that's not possible, then an
 exception at run-time. But a compilation error is much better).


If it were an error, I wouldn't let it go. A good use case is string 
tables - a formatted message may or may not use all of the available 
information.

Andrei

Apr 20 2009

bearophile <bearophileHUGS lycos.com> writes:

Andrei Alexandrescu:
 If it were an error, I wouldn't let it go.


It's an error. It will lead to troubles.

Bye,
bearophile

Apr 20 2009

BCS <ao pathlink.com> writes:

Reply to bearophile,

 Andrei Alexandrescu:
 
 If it were an error, I wouldn't let it go.
 


 
 Bye,
 bearophile


Then there need to be a way for the format string to use an argument without 
generating output for it because as Andrei is saying, there are real world 
cases where not using all the args is *normal* and not an error.

One option would be to not throw an error if the format string uses indexing 
formats (e.i. out of order formatting)

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

BCS wrote:
 Reply to bearophile,
 
 Andrei Alexandrescu:

 If it were an error, I wouldn't let it go.



 Bye,
 bearophile


 Then there need to be a way for the format string to use an argument 
 without generating output for it because as Andrei is saying, there are 
 real world cases where not using all the args is *normal* and not an error.
 
 One option would be to not throw an error if the format string uses 
 indexing formats (e.i. out of order formatting)


Yah, that's an option I considered. Maybe it's the best way to go.

Andrei

Apr 20 2009

"Nick Sabalausky" <a a.a> writes:

"Andrei Alexandrescu" <SeeWebsiteForEmail erdani.org> wrote in message 
news:gsiqdr$1csj$2 digitalmars.com...
 BCS wrote:
 Reply to bearophile,

 Andrei Alexandrescu:

 If it were an error, I wouldn't let it go.



 Bye,
 bearophile


 Then there need to be a way for the format string to use an argument 
 without generating output for it because as Andrei is saying, there are 
 real world cases where not using all the args is *normal* and not an 
 error.

 One option would be to not throw an error if the format string uses 
 indexing formats (e.i. out of order formatting)


 Yah, that's an option I considered. Maybe it's the best way to go.


That would be far too clumbsy, unless you made it into two separate 
functions.

For instance (psuedocode):
auto userInput = getUserInput()
// userInput now contains "{Name} at {Address}", zip deliberately ignored
writefln(userInput, name, address, zip); // They're used in-order, but there 
shouldn't be an error

Apr 20 2009

BCS <ao pathlink.com> writes:

Reply to Nick,

 "Andrei Alexandrescu" <SeeWebsiteForEmail erdani.org> wrote in message
 news:gsiqdr$1csj$2 digitalmars.com...
 
 BCS wrote:
 One option would be to not throw an error if the format string uses
 indexing formats (e.i. out of order formatting)
 


 


 functions.
 
 For instance (psuedocode):
 auto userInput = getUserInput()
 // userInput now contains "{Name} at {Address}", zip deliberately
 ignored
 writefln(userInput, name, address, zip); // They're used in-order, but
 there
 shouldn't be an error


They are in order but are listed by name so the error doesn't throw. The 
case where the error would be thrown is where the only format strings used 
are the "get the next arg" kind.

Apr 20 2009

"Nick Sabalausky" <a a.a> writes:

"BCS" <ao pathlink.com> wrote in message 
news:78ccfa2d3e68b8cb8fe69f8b7fba news.digitalmars.com...
 Reply to Nick,

 "Andrei Alexandrescu" <SeeWebsiteForEmail erdani.org> wrote in message
 news:gsiqdr$1csj$2 digitalmars.com...

 BCS wrote:
 One option would be to not throw an error if the format string uses
 indexing formats (e.i. out of order formatting)




 functions.

 For instance (psuedocode):
 auto userInput = getUserInput()
 // userInput now contains "{Name} at {Address}", zip deliberately
 ignored
 writefln(userInput, name, address, zip); // They're used in-order, but
 there
 shouldn't be an error


 They are in order but are listed by name so the error doesn't throw. The 
 case where the error would be thrown is where the only format strings used 
 are the "get the next arg" kind.


I was just using names for illustrative purposes. Also, I was under the 
impression that printf-style "get the next arg" formatting codes were the 
only ones writef supported. Is this not so?

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Nick Sabalausky wrote:
 "BCS" <ao pathlink.com> wrote in message 
 news:78ccfa2d3e68b8cb8fe69f8b7fba news.digitalmars.com...
 Reply to Nick,

 "Andrei Alexandrescu" <SeeWebsiteForEmail erdani.org> wrote in message
 news:gsiqdr$1csj$2 digitalmars.com...

 BCS wrote:
 One option would be to not throw an error if the format string uses
 indexing formats (e.i. out of order formatting)




 functions.

 For instance (psuedocode):
 auto userInput = getUserInput()
 // userInput now contains "{Name} at {Address}", zip deliberately
 ignored
 writefln(userInput, name, address, zip); // They're used in-order, but
 there
 shouldn't be an error


 case where the error would be thrown is where the only format strings used 
 are the "get the next arg" kind.


 I was just using names for illustrative purposes. Also, I was under the 
 impression that printf-style "get the next arg" formatting codes were the 
 only ones writef supported. Is this not so?
 
 


Since a few versions ago writef supports positional arguments with Posix 
syntax.

Andrei

Apr 20 2009

Georg Wrede <georg.wrede iki.fi> writes:

Andrei Alexandrescu wrote:
 Nick Sabalausky wrote:
 "BCS" <ao pathlink.com> wrote
 Reply to Nick,

 "Andrei Alexandrescu" <SeeWebsiteForEmail erdani.org> wrote in message
 news:gsiqdr$1csj$2 digitalmars.com...

 BCS wrote:
 One option would be to not throw an error if the format string uses
 indexing formats (e.i. out of order formatting)




 functions.

 For instance (psuedocode):
 auto userInput = getUserInput()
 // userInput now contains "{Name} at {Address}", zip deliberately
 ignored
 writefln(userInput, name, address, zip); // They're used in-order, but
 there
 shouldn't be an error


 The case where the error would be thrown is where the only format 
 strings used are the "get the next arg" kind.


 the impression that printf-style "get the next arg" formatting codes 
 were the only ones writef supported. Is this not so?


 syntax.
 
 Andrei


Positional format specifications really make a huge difference, 
especially where one needs to have the user interface in several 
languages. Thanks for them!!

Now, for the case without positional format specifications, we could 
(and I guess, should) have a solution to "the wrong number of arguments" 
problem. If we have:

  - a non-printing format spec
  - a munch-the-remaining-ones format spec
  - an ignore-too-few-arguments format spec

we could cover all the needed cases.

The first one lets you use one parameter without printing it. (Maybe you 
don't want to print the middle part of somebody's name.) The second is 
used when you don't want to print possibly many remaining arguments, say 
the address of someone, or the country.

The last one, is for the case where you use a single format string in 
several contexts, some of which you suspect may not contain enough 
information to be formally correct, but where you are satisfied to print 
an empty string '' (that is, not print anything) for them.

This situation might arise when the format string originates from 
outside the program.

** When none of the latter two are used, and there is the wrong number 
of arguments, I think a runtime exception should be thrown.

The only time where I think a compile time error is warranted, is when 
the format string is a string literal, with the wrong number of arguments.


The programmer may put the ignore-too-few-arguments format spec anywhere 
in the format string. Its effect starts from that point on.

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

bearophile wrote:
 Andrei Alexandrescu:
 If it were an error, I wouldn't let it go.


 It's an error. It will lead to troubles.


Well at most you could say it's error-prone, something that is easier to 
argue. The problem is that forcing it into an error makes quite a number 
of valid uses impossible. An example is a logging application that 
provides you a number of pieces of information (date, time, message, 
etc.) and you get to specify how they should be formatted. Oftentimes 
you'd choose to ignore some data.

Andrei

Apr 20 2009

Russell Lewis <webmaster villagersonline.com> writes:

Andrei Alexandrescu wrote:
 bearophile wrote:
 Andrei Alexandrescu:
 If it were an error, I wouldn't let it go.


 It's an error. It will lead to troubles.


 Well at most you could say it's error-prone, something that is easier to 
 argue. The problem is that forcing it into an error makes quite a number 
 of valid uses impossible. An example is a logging application that 
 provides you a number of pieces of information (date, time, message, 
 etc.) and you get to specify how they should be formatted. Oftentimes 
 you'd choose to ignore some data.
 
 Andrei


Fair enough.  But then let's split off a version of the function which 
allows unused arguments.  For most users, in most cases, unused 
arguments are indicative of an error.

Case in point: I have been bitten by this perhaps half a dozen times 
*already* porting older code.  This code used to work fine:

	writefln("The value is: %d", myVar, ".  Do something!");

Now, it interprets the trailing string as an unused argument, and 
ignores it (silently).  Ugh.

Ofc, looking back, I don't like that old coding style...I'm migrating 
back more to C-style (give the whole format string first).  But the fact 
that I had a *silent* error was frustrating.

Russ

Apr 20 2009

Lutger <lutger.blijdestijn gmail.com> writes:

Russell Lewis wrote:

...
 Case in point: I have been bitten by this perhaps half a dozen times 
 *already* porting older code.  This code used to work fine:
 
 	writefln("The value is: %d", myVar, ".  Do something!");
 



I bet a lot of to-be-ported D code will have this bug, I know my code will.  
When you want to print a format string this way - last argument(s) simply 
appended, it saves you two characters typing. When something saves any 
characters typing and produces the same result, programmers will do that.

Apr 21 2009

"Nick Sabalausky" <a a.a> writes:

"bearophile" <bearophileHUGS lycos.com> wrote in message 
news:gsipn1$1bng$1 digitalmars.com...
 Andrei Alexandrescu:
 If it were an error, I wouldn't let it go.


 It's an error. It will lead to troubles.


Sometimes it is an error, but there are times when it isn't:

Suppose you're writing a reporting module for an employee database:

---------------------
ID: 3234
Last: Doe
First: John
Phone: 555-5555
Zip: 90210

ID: 7642
Last: Smith
Etc...
---------------------

And you want the admins to be able to define their own reports:

---------------------
Privileged Report:
For Each Person: "ID #{ID}\nName: {First} {Last}\nPhone: {Phone}\nZip:{Zip}"

Unprivileged Report:
For Each Person: "Name: {Last}, {First}\nContact Info Classified"

Call List In Psuedo-Japanese:
For Each Person Where Name="Smith": "SmithSan {LoopIndex}'s DenwaBango: 
{Phone}"
---------------------

So then the report creation code:

---------------------
foreach(int i, Person p; people.subset(customReport.whereClause))
    writefln(customReport.formatStr, i, p.id, p.first, p.last, p.phone, 
p.zip);
---------------------

That would be very difficult/limiting if every arg had to be used in the 
format string.

(Incidentally, this example also demonstrates why I consider C#/Tango-style 
string formatting superior to C/Phobos-style)

Apr 20 2009

renoX <renosky free.fr> writes:

Nick Sabalausky a �crit :
 "bearophile" <bearophileHUGS lycos.com> wrote in message 
 news:gsipn1$1bng$1 digitalmars.com...
 Andrei Alexandrescu:
 If it were an error, I wouldn't let it go.




 Sometimes it is an error, but there are times when it isn't:


 Call List In Psuedo-Japanese:
 For Each Person Where Name="Smith": "SmithSan {LoopIndex}'s DenwaBango: 
 {Phone}"
 ---------------------
 
 So then the report creation code:
 
 ---------------------
 foreach(int i, Person p; people.subset(customReport.whereClause))
     writefln(customReport.formatStr, i, p.id, p.first, p.last, p.phone, 
 p.zip);
 ---------------------
 
 That would be very difficult/limiting if every arg had to be used in the 
 format string.


Mmmh, is {LoopIndex} correct? It should be {i} I think and I would argue 
that this format string should generate an error (something better than 
a runtime exception would be nice but I'm not sure that this is possible).

That said I agree that both are needed, so why not have either two 
different function or a function parameter which change the behaviour of 
the format string interpretation?

By default writefln would complain if there is a possibility of an 
unused parameter, but you could do
writefln(customReport.formatStr, i, p.id, p.first, p.last, p.phone, 
p.zip, allowUnused=true);

 (Incidentally, this example also demonstrates why I consider C#/Tango-style 
 string formatting superior to C/Phobos-style) 


I think that named format string are much superior to positional format 
string as they are easier to read/write..

BR,
renoX

Apr 27 2009

"Nick Sabalausky" <a a.a> writes:

"renoX" <renosky free.fr> wrote in message news:49F56A74.4000606 free.fr...
 Nick Sabalausky a �crit :
 "bearophile" <bearophileHUGS lycos.com> wrote in message 
 news:gsipn1$1bng$1 digitalmars.com...
 Andrei Alexandrescu:
 If it were an error, I wouldn't let it go.




 Sometimes it is an error, but there are times when it isn't:


 Call List In Psuedo-Japanese:
 For Each Person Where Name="Smith": "SmithSan {LoopIndex}'s DenwaBango: 
 {Phone}"
 ---------------------

 So then the report creation code:

 ---------------------
 foreach(int i, Person p; people.subset(customReport.whereClause))
     writefln(customReport.formatStr, i, p.id, p.first, p.last, p.phone, 
 p.zip);
 ---------------------

 That would be very difficult/limiting if every arg had to be used in the 
 format string.


 Mmmh, is {LoopIndex} correct? It should be {i} I think and I would argue 
 that this format string should generate an error (something better than a 
 runtime exception would be nice but I'm not sure that this is possible).


That was just for illustrative purposes.

 (Incidentally, this example also demonstrates why I consider 
 C#/Tango-style string formatting superior to C/Phobos-style)


 I think that named format string are much superior to positional format 
 string as they are easier to read/write..


Actually, I was referring to the ability to specify them out-of-order, 
repeat them, etc. (I didn't realize that Phobos's writef had recently gained 
that ability). To my knowledge, C#/Tango string formatting don't actually 
support named strings, only numerical ones. I was just using names for 
illustrative purposes, and (unclearly) implying that the app would translate 
those named formats into numerical ones before passing them along to the 
string output function.

Apr 27 2009

renoX <renosky free.fr> writes:

Nick Sabalausky a �crit :
 "bearophile" <bearophileHUGS lycos.com> wrote in message 
 news:gsipn1$1bng$1 digitalmars.com...
 Andrei Alexandrescu:
 If it were an error, I wouldn't let it go.




 Sometimes it is an error, but there are times when it isn't:


 Call List In Psuedo-Japanese:
 For Each Person Where Name="Smith": "SmithSan {LoopIndex}'s DenwaBango: 
 {Phone}"
 ---------------------
 
 So then the report creation code:
 
 ---------------------
 foreach(int i, Person p; people.subset(customReport.whereClause))
     writefln(customReport.formatStr, i, p.id, p.first, p.last, p.phone, 
 p.zip);
 ---------------------
 
 That would be very difficult/limiting if every arg had to be used in the 
 format string.


Mmmh, is {LoopIndex} correct? It should be {i} I think and I would argue 
that this format string should generate an error (something better than 
a runtime exception would be nice but I'm not sure that this is possible).

That said I agree that both are needed, so why not have either two 
different function or a function parameter which change the behaviour of 
the format string interpretation?

By default writefln would complain if there is a possibility of an 
unused parameter, but you could do
writefln(customReport.formatStr, i, p.id, p.first, p.last, p.phone, 
p.zip, allowUnused=true);

 (Incidentally, this example also demonstrates why I consider C#/Tango-style 
 string formatting superior to C/Phobos-style) 


I think that named format string are much superior to positional format 
string as they are easier to read/write..

BR,
renoX

Apr 27 2009

Daniel Keep <daniel.keep.lists gmail.com> writes:

bearophile wrote:
 BCS Wrote:
 Cool template function literals sounds interesting


 May I have one example of them?
 I am looking in the docs, but I am not finding anything...
 
 Bye,
 bearophile


If I had to guess, I'd say it was something like this:

 alias (T)(T a, T b) { return (a+b)/2.0; } average;


Haven't had a chance to TRY that yet, mind you.  :P

  -- Daniel

Apr 20 2009

Daniel Keep <daniel.keep.lists gmail.com> writes:

Daniel Keep wrote:
 
 bearophile wrote:
 BCS Wrote:
 Cool template function literals sounds interesting


 I am looking in the docs, but I am not finding anything...

 Bye,
 bearophile


 If I had to guess, I'd say it was something like this:
 
 alias (T)(T a, T b) { return (a+b)/2.0; } average;


 Haven't had a chance to TRY that yet, mind you.  :P
 
   -- Daniel


(Sees Walter's post)

Guess not.  :P

  -- Daniel

Apr 20 2009

Georg Wrede <georg.wrede iki.fi> writes:

Walter Bright wrote:
 
 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.
 
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Ooohhh, just half way through the change log, and already breathless!!!

Apr 20 2009

tama <repeatedly gmail.com> writes:

On Mon, 20 Apr 2009 18:12:16 +0900, Walter Bright  
<newshound1 digitalmars.com> wrote:

 bearophile wrote:
 BCS Wrote:
 Cool template function literals sounds interesting


 I am looking in the docs, but I am not finding anything...


 void foo(alias f)()
 {
      f(3, 4);
 }

 foo!((x,y){return x * y;))();


void foo(alias f)()
{
     writefln(f(3, 4));
}
foo!((x,y){ return x * y; })();

This code doesn't work(compile error). But, following code works.

void bar(alias f)()
{
     writefln(f("bar"));
}
bar!((str) { return str; })();

Is this a bug?

-- 
tama <repeatedly gmail.com>
http://profile.livedoor.com/repeatedly/
$B%a%s%P!<Jg=8Cf(B
http://tpf.techtalk.jp/

Apr 20 2009

tama <repeatedly gmail.com> writes:

bearophile wrote:
 tama:
 void foo(alias f)()
 {
      writefln(f(3, 4));
 }
 foo!((x,y){ return x * y; })();

 This code doesn't work(compile error).


 To me the following works:

 import std.stdio: writeln;
 void foo(alias f)() {
      writeln(f(3, 4));
 }
 void main() {
     foo!((x,y){ return x * y; })();
 }



I tested following code.

writefln(3 * 4);

This code doesn't work in the first place:-<
Sorry, it didn't matter.

-- 
tama <repeatedly gmail.com>
http://profile.livedoor.com/repeatedly/
$B%a%s%P!<Jg=8Cf(B
http://tpf.techtalk.jp/

Apr 20 2009

"Denis Koroskin" <2korden gmail.com> writes:

On Mon, 20 Apr 2009 14:58:38 +0400, tama <repeatedly gmail.com> wrote:

 bearophile wrote:
 tama:
 void foo(alias f)()
 {
      writefln(f(3, 4));
 }
 foo!((x,y){ return x * y; })();

 This code doesn't work(compile error).


 To me the following works:

 import std.stdio: writeln;
 void foo(alias f)() {
      writeln(f(3, 4));
 }
 void main() {
     foo!((x,y){ return x * y; })();
 }



 I tested following code.

 writefln(3 * 4);

 This code doesn't work in the first place:-<
 Sorry, it didn't matter.


writefln now expects a string as a first argument.
Use writeln() if you need no formattings, it is both faster and safer.

Apr 20 2009

tama <repeatedly gmail.com> writes:

Denis Koroskin wrote:
 writefln now expects a string as a first argument.
 Use writeln() if you need no formattings, it is both faster and safer.


I checked D2 changelog and founded it at version 2.006 and 2.029.

Thanks!

-- 
tama <repeatedly gmail.com>
http://profile.livedoor.com/repeatedly/
$B%a%s%P!<Jg=8Cf(B
http://tpf.techtalk.jp/

Apr 20 2009

"Saaa" <empty needmail.com> writes:

Using D1 feels especially retarded today :(

 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip

Apr 20 2009

Georg Wrede <georg.wrede iki.fi> writes:

Saaa wrote:
 Using D1 feels especially retarded today :(


Don't cry now. :-)
Soon you'll be using D2 for work, and cry when you see the D3 change log...

Apr 20 2009

Tomas Lindquist Olsen <tomas.l.olsen gmail.com> writes:

On Mon, Apr 20, 2009 at 2:47 PM, Saaa <empty needmail.com> wrote:
 Using D1 feels especially retarded today :(


Why retarded ?

Apr 20 2009

Georg Wrede <georg.wrede iki.fi> writes:

Walter Bright wrote:
 
 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.
 
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


The documentation for completeSort in std.algorithm says:

    Performs O(n * log(n)) (best case)
          to O(n * log(n)) (worst-case) evaluations of swap.

I wonder what it should be.

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Georg Wrede wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary 
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 The documentation for completeSort in std.algorithm says:
 
    Performs O(n * log(n)) (best case)
          to O(n * log(n)) (worst-case) evaluations of swap.
 
 I wonder what it should be.


Sorry, what was I thinking? I think (without being sure) that the
complexity of completeSort is O(rhs.length * log(t)) in the
best case, and O(t * log(t)) in the worst case, where t = lhs.length +
rhs.length.


Andrei

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Andrei Alexandrescu wrote:
 Georg Wrede wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary 
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 The documentation for completeSort in std.algorithm says:

    Performs O(n * log(n)) (best case)
          to O(n * log(n)) (worst-case) evaluations of swap.

 I wonder what it should be.


 Sorry, what was I thinking? I think (without being sure) that the
 complexity of completeSort is O(rhs.length * log(t)) in the
 best case, and O(t * log(t)) in the worst case, where t = lhs.length +
 rhs.length.


I revise that. Best case, there's temporary memory to allocate and then 
the complexity is that of sorting rhs plus merge lhs and rhs using extra 
memory. That is O(lhs.length + rhs.length * log(rhs.length)).

Worst case, there's no temporary memory available so we need to sort the 
whole thing. That means O((lhs.length + rhs.length) * log(rhs.length + 
rhs.length)).

I committed the fixed module.


Andrei

Apr 20 2009

dsimcha <dsimcha yahoo.com> writes:

== Quote from Walter Bright (newshound1 digitalmars.com)'s article
 This is a major revision to Phobos, including Andrei's revolutionary new
 range support.
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Two small issues I've just run into that might warrant a quick update:

Line 908 in random.d calls the deprecated rand_seed() for the old school random
number generators from the static constructor.  This means that std.random just
plain can't be used out of the box.

Also, when using std.string, I get the following linker errors on the Win32
build:


Symbol Undefined _D3std6string6striprFAyaZAya
Symbol Undefined _D3std6string6striplFAyaZAya

Apr 20 2009

dsimcha <dsimcha yahoo.com> writes:

== Quote from dsimcha (dsimcha yahoo.com)'s article
 == Quote from Walter Bright (newshound1 digitalmars.com)'s article
 This is a major revision to Phobos, including Andrei's revolutionary new
 range support.
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Line 908 in random.d calls the deprecated rand_seed() for the old school random
 number generators from the static constructor.  This means that std.random just
 plain can't be used out of the box.
 Also, when using std.string, I get the following linker errors on the Win32
build:
 Symbol Undefined _D3std6string6striprFAyaZAya
 Symbol Undefined _D3std6string6striplFAyaZAya


Never mind on the linker error.  That was caused by me forgetting to recompile
parts of my code.  The random thing looks legit, though.

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

dsimcha wrote:
 == Quote from dsimcha (dsimcha yahoo.com)'s article
 == Quote from Walter Bright (newshound1 digitalmars.com)'s article
 This is a major revision to Phobos, including Andrei's revolutionary new
 range support.
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Line 908 in random.d calls the deprecated rand_seed() for the old school random
 number generators from the static constructor.  This means that std.random just
 plain can't be used out of the box.
 Also, when using std.string, I get the following linker errors on the Win32
build:
 Symbol Undefined _D3std6string6striprFAyaZAya
 Symbol Undefined _D3std6string6striplFAyaZAya


 Never mind on the linker error.  That was caused by me forgetting to recompile
 parts of my code.  The random thing looks legit, though.


Ok, I've undeprecated rand_seed, sigh. I was hoping I'd eliminate rand() 
entirely from this release, but Walter pointed out it would break too 
much code. So I left rand() and rand_seed() as deprecated. Now I only 
left rand() deprecated so at least the static constructor works.


Andrei

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

Andrei Alexandrescu wrote:
 Ok, I've undeprecated rand_seed, sigh. I was hoping I'd eliminate rand() 
 entirely from this release, but Walter pointed out it would break too 
 much code. So I left rand() and rand_seed() as deprecated. Now I only 
 left rand() deprecated so at least the static constructor works.


I think the right fix for that is for the compiler to not complain about 
deprecated symbol usage if the usage is in the same module the 
deprecated symbol is defined in.

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

http://d.puremagic.com/issues/show_bug.cgi?id=2864

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Walter Bright wrote:
 Andrei Alexandrescu wrote:
 Ok, I've undeprecated rand_seed, sigh. I was hoping I'd eliminate 
 rand() entirely from this release, but Walter pointed out it would 
 break too much code. So I left rand() and rand_seed() as deprecated. 
 Now I only left rand() deprecated so at least the static constructor 
 works.


 I think the right fix for that is for the compiler to not complain about 
 deprecated symbol usage if the usage is in the same module the 
 deprecated symbol is defined in.


Reading this, I thought "No chance Walter will ever do this" until I saw 
the poster's name :o).

Andrei

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

Andrei Alexandrescu wrote:
 Walter Bright wrote:
 I think the right fix for that is for the compiler to not complain 
 about deprecated symbol usage if the usage is in the same module the 
 deprecated symbol is defined in.


 Reading this, I thought "No chance Walter will ever do this" until I saw 
 the poster's name :o).


It is consistent with the ideas behind private access. Presumably the 
person working on the module knows what they're doing, no need to hide 
it from himself.

Apr 20 2009

"Craig Black" <craigblack2 cox.net> writes:

I like very much the direction D2 is going now.  Language refactoring and 
enhancements driven by the goal of more elegant implementation of standard 
libraries.  This approach seems very practical and promising.  Thank you 
very much and keep it up!

-Craig

Apr 20 2009

superdan <super dan.org> writes:

Craig Black Wrote:

 I like very much the direction D2 is going now.  Language refactoring and 
 enhancements driven by the goal of more elegant implementation of standard 
 libraries.  This approach seems very practical and promising.  Thank you 
 very much and keep it up!
 
 -Craig 


holy guacashit this works.

import std.algorithm;
import std.range;
import std.stdio;

void main()
{
    string[] a = [ "shit", "poop" ];
    string[] b = [ "dump", "shite" ];
    sort!((a, b) { return a > b; })(chain(a, b));
    writeln(a, " ", b);
}

i'll be shat on. couple shitty problems tho. auto don't work shit for a and b.
complains about fixed size strings'n'shit. then writeln(chain(a, b)) shites
ChainImpl!(immutable(char)[][],immutable(char)[][]) to stdout. tat's liable to
scare da shit outta a beginner.

Apr 20 2009

downs <default_357-line yahoo.de> writes:

superdan wrote:
 Craig Black Wrote:
 
 I like very much the direction D2 is going now.  Language refactoring and 
 enhancements driven by the goal of more elegant implementation of standard 
 libraries.  This approach seems very practical and promising.  Thank you 
 very much and keep it up!

 -Craig 


 holy guacashit this works.
 
 import std.algorithm;
 import std.range;
 import std.stdio;
 
 void main()
 {
     string[] a = [ "shit", "poop" ];
     string[] b = [ "dump", "shite" ];
     sort!((a, b) { return a > b; })(chain(a, b));
     writeln(a, " ", b);
 }
 
 i'll be shat on. couple shitty problems tho. auto don't work shit for a and b.
complains about fixed size strings'n'shit. then writeln(chain(a, b)) shites
ChainImpl!(immutable(char)[][],immutable(char)[][]) to stdout. tat's liable to
scare da shit outta a beginner.
 


Poop is funny! :)

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

superdan wrote:
 Craig Black Wrote:
 
 I like very much the direction D2 is going now.  Language refactoring and 
 enhancements driven by the goal of more elegant implementation of standard 
 libraries.  This approach seems very practical and promising.  Thank you 
 very much and keep it up!

 -Craig 


 holy guacashit this works.
 
 import std.algorithm;
 import std.range;
 import std.stdio;
 
 void main()
 {
     string[] a = [ "shit", "poop" ];
     string[] b = [ "dump", "shite" ];
     sort!((a, b) { return a > b; })(chain(a, b));
     writeln(a, " ", b);
 }
 
 i'll be shat on. couple shitty problems tho. auto don't work shit for a and b.
complains about fixed size strings'n'shit. then writeln(chain(a, b)) shites
ChainImpl!(immutable(char)[][],immutable(char)[][]) to stdout. tat's liable to
scare da shit outta a beginner.
 


Thanks... I guess :o). Any chance you could submit the issues to 
bugzilla? I think the problem with string arrays is already known, but I 
need a memento to make writeln work with ranges.

Andrei

Apr 20 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Craig Black wrote:
 I like very much the direction D2 is going now.  Language refactoring 
 and enhancements driven by the goal of more elegant implementation of 
 standard libraries.  This approach seems very practical and promising.  
 Thank you very much and keep it up!
 
 -Craig


Thanks. Walter pointed out to me something interesting - STL is 
non-intuitive. That doesn't make it any less true (as a pursuit of the 
most generic incarnation of fundamental structs and algos). It's 
non-intuitive the same way complex numbers and relativity theory are 
non-intuitive.

No language has ever managed to comprehend STL by sheer chance. (This in 
spite of e.g. C# adding a boatload of new features with each release.) 
There are two that can express it at all: C++ and D. Both C++ and D had 
to be changed to allow STL to exist, and became better languages as a 
result. The range shtick and D's support for lambdas is taking STL 
support to a whole new level.

The downside is, it's rather difficult to explain the STL to anyone 
using other languages and wanting to just figure what the STL buzz is 
all about.


Andrei

Apr 20 2009

Georg Wrede <georg.wrede iki.fi> writes:

Andrei Alexandrescu wrote:
 Craig Black wrote:
 I like very much the direction D2 is going now.  Language refactoring 
 and enhancements driven by the goal of more elegant implementation of 
 standard libraries.  This approach seems very practical and 
 promising.  Thank you very much and keep it up!

 -Craig


 Thanks. Walter pointed out to me something interesting - STL is 
 non-intuitive. That doesn't make it any less true (as a pursuit of the 
 most generic incarnation of fundamental structs and algos). It's 
 non-intuitive the same way complex numbers and relativity theory are 
 non-intuitive.
 
 No language has ever managed to comprehend STL by sheer chance. (This in 
 spite of e.g. C# adding a boatload of new features with each release.) 
 There are two that can express it at all: C++ and D. Both C++ and D had 
 to be changed to allow STL to exist, and became better languages as a 
 result. The range shtick and D's support for lambdas is taking STL 
 support to a whole new level.
 
 The downside is, it's rather difficult to explain the STL to anyone 
 using other languages and wanting to just figure what the STL buzz is 
 all about.


I wrote my MSc thesis about the STL. I think the conceptual idea was 
clean and clear, and at the time it was reasonably easy to explain it to 
even the professors. ;-)

Today, however, and especially with the advanced implementation we have 
here in D, if someone has no prior knowledge of the STL way of thinking, 
it may be really hard to get them to 'get it'. There are too many trees 
up front to grasp the forest.

What's sad, http://en.wikipedia.org/wiki/Standard_Template_Library
really sucks at introducing the STL on a conceptual level. Even worse, 
that is actually the only thing it *should* do. Everyting else is optional.

Apr 20 2009

Leandro Lucarella <llucax gmail.com> writes:

Georg Wrede, el 21 de abril a las 09:25 me escribiste:
 What's sad, http://en.wikipedia.org/wiki/Standard_Template_Library
 really sucks at introducing the STL on a conceptual level. Even worse, that is 
 actually the only thing it *should* do. Everyting else is optional.


You should improve it then =)

-- 
Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/
----------------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145  104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------------

Apr 21 2009

Georg Wrede <georg.wrede iki.fi> writes:

Walter Bright wrote:

In std.array, the example for back() is the same as for front().


The example for put() seems to be correct (and put() behaves 
accordingly), however, the asserted results are not what the reader 
would expect.

If we are verbose enough to explain the dot notation here, then it would 
be prudent to elaborate a little as to the point of put(), and possibly 
the example (or the explanation) could include a use case.

Apr 20 2009

Russell Lewis <webmaster villagersonline.com> writes:

Walter Bright wrote:
 
 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.
 
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Was fwritefln() removed intentionally?  Or should I write up a Bugzilla? 
  I didn't noteice a mention in changelog.

Apr 19 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Russell Lewis wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary 
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Was fwritefln() removed intentionally?  Or should I write up a Bugzilla? 
  I didn't noteice a mention in changelog.


Sorry. It was removed intentionally along with all functions that 
manipulate FILE* directly.

Its functional equivalent is File.writefln. If all you have is a handle, 
use File.wrapFile(fhandle).writefln.


Andrei

Apr 20 2009

annoyed <abc email.com> writes:

It's in dmd-v2.026/src/phobos/std/stdio.d:void fwritefln(FILE* fp, ...)

but I cannot find it in 2.029.

Apr 20 2009

Tyro[a.c.edwards] <nospam home.com> writes:

annoyed Wrote:

 It's in dmd-v2.026/src/phobos/std/stdio.d:void fwritefln(FILE* fp, ...)
 
 but I cannot find it in 2.029.
 


It was removed, use File.writefln() instead. std.stdio has been rewritten so
you might want to take a look at the docs.

Andrew

Apr 20 2009

Stewart Gordon <smjg_1998 yahoo.com> writes:

Walter, how often do you update your working copy from the SVN? 
Obviously less than once every 2 releases.

Stewart.

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

Stewart Gordon wrote:
 Walter, how often do you update your working copy from the SVN? 
 Obviously less than once every 2 releases.


As far as I know, it is current. Everything got checked in.

Apr 20 2009

BCS <none anon.com> writes:

Hello Walter,

 Stewart Gordon wrote:
 
 Walter, how often do you update your working copy from the SVN?
 Obviously less than once every 2 releases.
 


 


I think he was asking about the otherway (not that I known why)

Apr 20 2009

Walter Bright <newshound1 digitalmars.com> writes:

BCS wrote:
 I think he was asking about the otherway (not that I known why)


I think he'll need to be more specific!

Apr 20 2009

"Unknown W. Brackets" <unknown simplemachines.org> writes:

Well, there's push (svn commit) and pull (svn up), so he must mean one 
or the other...

-[Unknown]


Walter Bright wrote:
 BCS wrote:
 I think he was asking about the otherway (not that I known why)


 I think he'll need to be more specific!

Apr 20 2009

Stewart Gordon <smjg_1998 yahoo.com> writes:

Walter Bright wrote:
 Stewart Gordon wrote:
 Walter, how often do you update your working copy from the SVN? 
 Obviously less than once every 2 releases.


 As far as I know, it is current. Everything got checked in.


So how has the fix for
http://d.puremagic.com/issues/show_bug.cgi?id=2580
(and probably others) not been included?

Stewart.

Apr 21 2009

Walter Bright <newshound1 digitalmars.com> writes:

Stewart Gordon wrote:
 So how has the fix for
 http://d.puremagic.com/issues/show_bug.cgi?id=2580
 (and probably others) not been included?


I'll look into it.

Apr 27 2009

Sean Kelly <sean invisibleduck.org> writes:

Stewart Gordon wrote:
 Walter Bright wrote:
 Stewart Gordon wrote:
 Walter, how often do you update your working copy from the SVN? 
 Obviously less than once every 2 releases.


 As far as I know, it is current. Everything got checked in.


 So how has the fix for
 http://d.puremagic.com/issues/show_bug.cgi?id=2580
 (and probably others) not been included?


The code fix for this is in.  You can see it in 
dmd/src/compiler/dmd/dmain2.d: rt_init().  I haven't updated the 
documentation yet though (this last release took me a bit by 
surprise)--I'll take care of that before the next release.

Apr 27 2009

Max Samukha <samukha voliacable.com.removethis> writes:

On Mon, 20 Apr 2009 00:09:09 -0700, Walter Bright
<newshound1 digitalmars.com> wrote:

This is a major revision to Phobos, including Andrei's revolutionary new 
range support.

http://www.digitalmars.com/d/2.0/changelog.html
http://ftp.digitalmars.com/dmd.2.029.zip


Wicked awesome!

file:///C:/dmd/html/d/phobos/std_range.html#cons
Looks like bug 2676 was fixed in 2.027

Apr 20 2009

Max Samukha <samukha voliacable.com.removethis> writes:

On Mon, 20 Apr 2009 09:57:55 +0200, Max Samukha
<samukha voliacable.com.removethis> wrote:

On Mon, 20 Apr 2009 00:09:09 -0700, Walter Bright
<newshound1 digitalmars.com> wrote:

This is a major revision to Phobos, including Andrei's revolutionary new 
range support.

http://www.digitalmars.com/d/2.0/changelog.html
http://ftp.digitalmars.com/dmd.2.029.zip


Wicked awesome!

file:///C:/dmd/html/d/phobos/std_range.html#cons



Looks like bug 2676 was fixed in 2.027

Apr 21 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Max Samukha wrote:
 On Mon, 20 Apr 2009 09:57:55 +0200, Max Samukha
 <samukha voliacable.com.removethis> wrote:
 
 On Mon, 20 Apr 2009 00:09:09 -0700, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip



 file:///C:/dmd/html/d/phobos/std_range.html#cons


 
 Looks like bug 2676 was fixed in 2.027




Thanks. I uncommented the unittest, updated the doc, and checked in.

Andrei

Apr 21 2009

Max Samukha <samukha voliacable.com.removethis> writes:

On Tue, 21 Apr 2009 07:42:46 -0500, Andrei Alexandrescu
<SeeWebsiteForEmail erdani.org> wrote:

Max Samukha wrote:
 On Mon, 20 Apr 2009 09:57:55 +0200, Max Samukha
 <samukha voliacable.com.removethis> wrote:
 
 On Mon, 20 Apr 2009 00:09:09 -0700, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip



 file:///C:/dmd/html/d/phobos/std_range.html#cons


 
 Looks like bug 2676 was fixed in 2.027




Thanks. I uncommented the unittest, updated the doc, and checked in.

Andrei


A couple more minor doc issues:
http://www.digitalmars.com/d/2.0/phobos/std_range.html: instances of
"the popFront" need to be corrected to "the next".

On the std.algorithm page, the examples for "map" and "filter" don't
compile due to the fixed size array in equal().

The example for "bringToFront" is outdated.

The comments for "remove": "If $(s =" -> "If $(D s ="

Apr 22 2009

Max Samukha <samukha voliacable.com.removethis> writes:

On Wed, 22 Apr 2009 00:32:27 -0700, Brad Roberts
<braddr puremagic.com> wrote:

Max Samukha wrote:
 On Tue, 21 Apr 2009 07:42:46 -0500, Andrei Alexandrescu
 <SeeWebsiteForEmail erdani.org> wrote:
 
 Max Samukha wrote:
 On Mon, 20 Apr 2009 09:57:55 +0200, Max Samukha
 <samukha voliacable.com.removethis> wrote:

 On Mon, 20 Apr 2009 00:09:09 -0700, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip



 file:///C:/dmd/html/d/phobos/std_range.html#cons



 Looks like bug 2676 was fixed in 2.027





 Andrei


 A couple more minor doc issues:
 http://www.digitalmars.com/d/2.0/phobos/std_range.html: instances of
 "the popFront" need to be corrected to "the next".
 
 On the std.algorithm page, the examples for "map" and "filter" don't
 compile due to the fixed size array in equal().
 
 The example for "bringToFront" is outdated.
 
 The comments for "remove": "If $(s =" -> "If $(D s ="


Please file a bug report.  Posts here are are good way for issues to
fall through the cracks.

Thanks,
Brad


done http://d.puremagic.com/issues/show_bug.cgi?id=2874

Apr 22 2009

Brad Roberts <braddr puremagic.com> writes:

Max Samukha wrote:
 On Tue, 21 Apr 2009 07:42:46 -0500, Andrei Alexandrescu
 <SeeWebsiteForEmail erdani.org> wrote:
 
 Max Samukha wrote:
 On Mon, 20 Apr 2009 09:57:55 +0200, Max Samukha
 <samukha voliacable.com.removethis> wrote:

 On Mon, 20 Apr 2009 00:09:09 -0700, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip



 file:///C:/dmd/html/d/phobos/std_range.html#cons



 Looks like bug 2676 was fixed in 2.027





 Andrei


 A couple more minor doc issues:
 http://www.digitalmars.com/d/2.0/phobos/std_range.html: instances of
 "the popFront" need to be corrected to "the next".
 
 On the std.algorithm page, the examples for "map" and "filter" don't
 compile due to the fixed size array in equal().
 
 The example for "bringToFront" is outdated.
 
 The comments for "remove": "If $(s =" -> "If $(D s ="


Please file a bug report.  Posts here are are good way for issues to
fall through the cracks.

Thanks,
Brad

Apr 22 2009

"Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:

Walter Bright wrote:
 
 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.
 
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


This is looking very nice! I want to switch from D1 to D2, but...

I don't want to sound greedy or anything, and I know others have asked 
for this before, but is making a 64-bit Linux version of DMD a lot of work?

I admit I don't know much about these things, and what I'm going to say 
next may not make sense at all, but here goes:

x86-64 is just a superset of x86, right? Wouldn't it be possible, as a 
first step in the direction of a full-fledged x86-64 compiler, to simply 
make one that uses the same instruction set as the current DMD, but, I 
dunno, marks the executable as 64-bit (or something like that)? 
Specialisation and optimisation for the 64-bit architecture could then 
come at a later point in time.

I know it is possible to run the 32-bit compiler (and the executables it 
produces) on a 64-bit operating system, but it isn't possible to link 
against 64-bit libraries. This means that one has to install and 
maintain 32-bit versions of all the libraries one wants to use, and 
those are, in general, not available through the repositories of most 
64-bit distros.

-Lars

Apr 21 2009

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:

Lars T. Kyllingstad wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary 
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 This is looking very nice! I want to switch from D1 to D2, but...
 
 I don't want to sound greedy or anything, and I know others have asked 
 for this before, but is making a 64-bit Linux version of DMD a lot of work?
 
 I admit I don't know much about these things, and what I'm going to say 
 next may not make sense at all, but here goes:
 
 x86-64 is just a superset of x86, right? Wouldn't it be possible, as a 
 first step in the direction of a full-fledged x86-64 compiler, to simply 
 make one that uses the same instruction set as the current DMD, but, I 
 dunno, marks the executable as 64-bit (or something like that)? 
 Specialisation and optimisation for the 64-bit architecture could then 
 come at a later point in time.


It's not quite that simple. It's not a full superset; some x86 instructions are 
not valid x86-64 instructions.
For example, I think 'inc' was removed to make place for prefixes that set some 
flags for the next instruction and allow it to use the extra registers r8-r15.

Apr 21 2009

Daniel Keep <daniel.keep.lists gmail.com> writes:

Lars T. Kyllingstad wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 This is looking very nice! I want to switch from D1 to D2, but...
 
 I don't want to sound greedy or anything, and I know others have asked
 for this before, but is making a 64-bit Linux version of DMD a lot of work?
 
 I admit I don't know much about these things, and what I'm going to say
 next may not make sense at all, but here goes:
 
 x86-64 is just a superset of x86, right? Wouldn't it be possible, as a
 first step in the direction of a full-fledged x86-64 compiler, to simply
 make one that uses the same instruction set as the current DMD, but, I
 dunno, marks the executable as 64-bit (or something like that)?
 Specialisation and optimisation for the 64-bit architecture could then
 come at a later point in time.


I'm pretty sure that 64-bit code is binary incompatible with 32-bit
code.  For example:

struct Foo { void* ptr; }

Is a different size for 32-bit and 64-bit code.

 I know it is possible to run the 32-bit compiler (and the executables it
 produces) on a 64-bit operating system, but it isn't possible to link
 against 64-bit libraries. This means that one has to install and
 maintain 32-bit versions of all the libraries one wants to use, and
 those are, in general, not available through the repositories of most
 64-bit distros.


This is because the OS puts the CPU into a 32-bit compatible mode, but
it can't magic away the differences between 32-bit and 64-bit code.

 -Lars


The best bet for 64-bit D executables at this point is probably LDC;
dunno what the current state is, though.

  -- Daniel

Apr 21 2009

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:

Daniel Keep wrote:
 
 Lars T. Kyllingstad wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip






 
 The best bet for 64-bit D executables at this point is probably LDC;
 dunno what the current state is, though.


The state for D2 is currently "very broken", AFAIK.

Apr 21 2009

Lutger <lutger.blijdestijn gmail.com> writes:

Daniel Keep wrote:

...
 -Lars


 The best bet for 64-bit D executables at this point is probably LDC;
 dunno what the current state is, though.
 
   -- Daniel


if you grep the dmd backend sources for x86_64, you'll get some results. 
Don't know what that means though, the source looks like magic to me!

Apr 21 2009

Don <nospam nospam.com> writes:

Lutger wrote:
 Daniel Keep wrote:
 
 ...
 -Lars


 dunno what the current state is, though.

   -- Daniel


 if you grep the dmd backend sources for x86_64, you'll get some results. 
 Don't know what that means though, the source looks like magic to me!
 
 


code generation. Much more fun is:
$ cd src/dmd
$ grep "goto " * -R

Apr 21 2009

Lutger <lutger.blijdestijn gmail.com> writes:

Don wrote:

 Lutger wrote:
 Daniel Keep wrote:
 
 ...
 -Lars


 dunno what the current state is, though.

   -- Daniel


 if you grep the dmd backend sources for x86_64, you'll get some results. 
 Don't know what that means though, the source looks like magic to me!
 
 


 code generation. Much more fun is:
 $ cd src/dmd
 $ grep "goto " * -R


 you forgot " | less" there, what the hell...this code can't be human.

Apr 21 2009

Walter Bright <newshound1 digitalmars.com> writes:

Lutger wrote:
 what the hell...this code can't be human.


I was replaced by Colossus years ago.

Apr 21 2009

Georg Wrede <georg.wrede iki.fi> writes:

Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


Michael A. Jackson wouldn't approve 1175 gotos in 113 files.

Apr 21 2009

Don <nospam nospam.com> writes:

Georg Wrede wrote:
 Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


 Michael A. Jackson wouldn't approve 1175 gotos in 113 files.


It'd be really funny to pass it through one of those "code quality" 
metrics, one of the ones with a ridiculously heavy penalty for using 
goto. I think it'd tell you that DMD source is almost the lowest-quality 
code on the planet. <g>

Actually, looking through the DMD source it becomes obvious that goto is 
really not a problem at all. The lack of comments is much more of a 
problem. (Especially with files with names like "e2ir.c". What the heck 
is "fltables.c", "cdxxx.c", "elxxx.c" ?). Even so, it's mostly not that 
difficult to understand.

Apr 22 2009

Georg Wrede <georg.wrede iki.fi> writes:

Don wrote:
 Georg Wrede wrote:
 Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


 Michael A. Jackson wouldn't approve 1175 gotos in 113 files.


 It'd be really funny to pass it through one of those "code quality" 
 metrics, one of the ones with a ridiculously heavy penalty for using 
 goto. I think it'd tell you that DMD source is almost the lowest-quality 
 code on the planet. <g>


Yeah. But now I'm getting a bad conscience, this is beginning to look 
like Walter-bashing... :-)

 Actually, looking through the DMD source it becomes obvious that goto is 
 really not a problem at all. The lack of comments is much more of a 
 problem. (Especially with files with names like "e2ir.c". What the heck 
 is "fltables.c", "cdxxx.c", "elxxx.c" ?). Even so, it's mostly not that 
 difficult to understand.


I guess Walter has to keep alternating between ASM, C and D. And a lot 
of ASM coding is nothing more than a bunch of MOV and JMP stuff. And 
file naming conventions here look like what one typically finds in 
development code (before some pre-publishing guy has tidyed it up with a 
lot of global search&replaces). And, after all, the C files never were 
meant to be public anyway.

Actually, the one interesting question might be, would rewriting this 
code in a structured fashion (I mean, removing the gotos) make it 
slower? (Not that I'd be suggesting Walter should do it. Just an 
academic question.)

Apr 22 2009

Don <nospam nospam.com> writes:

Georg Wrede wrote:
Don wrote:
Georg Wrede wrote:
Walter Bright wrote:
Lutger wrote:
what the hell...this code can't be human.

I was replaced by Colossus years ago.

Michael A. Jackson wouldn't approve 1175 gotos in 113 files.

It'd be really funny to pass it through one of those "code quality"
metrics, one of the ones with a ridiculously heavy penalty for using
goto. I think it'd tell you that DMD source is almost the
lowest-quality code on the planet. <g>

Yeah. But now I'm getting a bad conscience, this is beginning to look
like Walter-bashing... :-)

I think those code quality metrics are ridiculous. The prejudice against
'goto' is really just brainwashing and totally without basis.

Here's a recent link from Andrew Koenig, who really should know better.

http://dobbscodetalk.com/index.php?option=com_myblog&show=What-Dijkstra-said-was-harmful-about-goto-statements.html&Itemid=29

Can you see his fundamental mistake? He talks about "the program" (just
as Dijkstra said), but it's just not relevant for C/C++/D/Pascal/...
or any other structured programming language. Wherever he says "program"
you should substitute "function". And then the force of the argument
totally disappears.

The problem with goto in an unstructured language is that when you see a
label, you don't know where it came from. It could be anywhere in the
entire program (maybe a million lines of code!) And that's a complete
disaster. But in a structured language, you know it's from somewhere in
the function.
And this is no different from any other control structure. You ALWAYS
have to look at the whole scope you're in.

void foo(){
int n;
bool b = true;
while (b) {
if (n==4) { /* when do we get here? You have to read the whole
function to find out. Where does n get modified? */ }
:
:
:
}
}

Heck, even in inline ASM in D, you can't write the kind of spaghetti
code Dijkstra was complaining about. You always have local scope.

Yet, I personally have been so affected by anti-goto brainwashing that
I've never used goto in C, C++, or D. But I gradually realised that it
was just brainwashing. I've never experienced any problem with goto in ASM.

Actually, looking through the DMD source it becomes obvious that goto
is really not a problem at all. The lack of comments is much more of a
problem. (Especially with files with names like "e2ir.c". What the
heck is "fltables.c", "cdxxx.c", "elxxx.c" ?). Even so, it's mostly
not that difficult to understand.

I guess Walter has to keep alternating between ASM, C and D. And a lot
of ASM coding is nothing more than a bunch of MOV and JMP stuff. And
file naming conventions here look like what one typically finds in
development code (before some pre-publishing guy has tidyed it up with a
lot of global search&replaces). And, after all, the C files never were
meant to be public anyway.

Actually, the one interesting question might be, would rewriting this
code in a structured fashion (I mean, removing the gotos) make it
slower? (Not that I'd be suggesting Walter should do it. Just an
academic question.)

I doubt it'd affect the speed at all. It'd probably make it longer.
There are cases in DMD where it seems to make the control flow simpler.

Apr 22 2009

Georg Wrede <georg.wrede iki.fi> writes:

Don wrote:
 Georg Wrede wrote:
 Don wrote:
 Georg Wrede wrote:
 Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


 Michael A. Jackson wouldn't approve 1175 gotos in 113 files.


 It'd be really funny to pass it through one of those "code quality" 
 metrics, one of the ones with a ridiculously heavy penalty for using 
 goto. I think it'd tell you that DMD source is almost the 
 lowest-quality code on the planet. <g>


 Yeah. But now I'm getting a bad conscience, this is beginning to look 
 like Walter-bashing... :-)


 I think those code quality metrics are ridiculous. The prejudice against 
 'goto' is really just brainwashing and totally without basis.


Well, at the time, they had no choice. Unstructured code was the norm, 
and people who tangled themselves in spaghetti never noticed it's 
because of goto usage. Instead they just preceived programming as hard.

The language on my first computer was old fashioned BASIC, with line 
numbers and no named subroutines or structural elements. I felt that the 
effort needed to program was exponential to the number of lines. In 
hindsight, that must have been entirely because I'd had no higher 
education in programming, no notion of structuring the code (in any 
particular way), etc. But the absolutely worst thing was that one 
couldn't pass parameters to subroutines. (gosub <lineNumber>) And all 
variables were global.

In those days most programming was done in COBOL, by (essentially) 
non-programmers. (The idea of COBOL was, after all, to be usable by 
business people, not MSc programmers.) Jackson had to change not only 
the methodology, but before that, the concept and the motivation for 
using structured programming. That was the hard part, and it needed some 
serious evangelising and brainwashing, to overcome the inertia.

Unfortunately, that meant murdering, dismembering, and pulverizing any 
least hint of even thinking about using goto. And as with any paradigm 
shift, the disciples took it to religious extremes.

 Here's a recent link from Andrew Koenig, who really should know better.
 
 http://dobbscodetalk.com/index.php?option=com_myblog&show=What-Dijkstra-said-was-harmful-about-goto-state
ents.html&Itemid=29 
 
 Can you see his fundamental mistake? He talks about "the program" (just 
 as Dijkstra said), but it's just not relevant for C/C++/D/Pascal/...
 or any other structured programming language. Wherever he says "program" 
 you should substitute "function". And then the force of the argument 
 totally disappears.


Yes.

 The problem with goto in an unstructured language is that when you see a 
 label, you don't know where it came from. It could be anywhere in the 
 entire program (maybe a million lines of code!) And that's a complete 
 disaster. But in a structured language, you know it's from somewhere in 
 the function.
 And this is no different from any other control structure. You ALWAYS 
 have to look at the whole scope you're in.
 
 void foo(){
  int n;
 bool b = true;
   while (b) {
     if (n==4) {   /* when do we get here? You have to read the whole 
 function to find out. Where does n get modified? */ }
 :
 :
 :
   }
 }
 
 Heck, even in inline ASM in D, you can't write the kind of spaghetti 
 code Dijkstra was complaining about. You always have local scope.


OTOH, getting the algorithm may become tedious even in small snippets. 
For example, here's Algorithm M, from /Fundamental Algorithms/, Knuth 
1969, page 95:

     M1: int j=n; int k=n; int m=X[n];
     M2: if(k==0) goto M6;
     M3: if(X[k] <= m) goto M5;
     M4: j=k; m=X[k];
     M5: k--; goto M2;
     M6: ;

That's three gotos for six lines. How long did it take to fully figure 
out what it's doing? Way longer than if it were written in structured D, 
anyway.

 Yet, I personally have been so affected by anti-goto brainwashing that 
 I've never used goto in C, C++, or D. But I gradually realised that it 
 was just brainwashing. I've never experienced any problem with goto in ASM.


Same here. Last time I used it was in Pascal, and boy, did I have a bad 
conscience. It felt like I was doing something Mom has forbidden.

 Actually, looking through the DMD source it becomes obvious that goto 
 is really not a problem at all. The lack of comments is much more of 
 a problem. (Especially with files with names like "e2ir.c". What the 
 heck is "fltables.c", "cdxxx.c", "elxxx.c" ?). Even so, it's mostly 
 not that difficult to understand.


 I guess Walter has to keep alternating between ASM, C and D. And a lot 
 of ASM coding is nothing more than a bunch of MOV and JMP stuff. And 
 file naming conventions here look like what one typically finds in 
 development code (before some pre-publishing guy has tidyed it up with 
 a lot of global search&replaces). And, after all, the C files never 
 were meant to be public anyway.

 Actually, the one interesting question might be, would rewriting this 
 code in a structured fashion (I mean, removing the gotos) make it 
 slower? (Not that I'd be suggesting Walter should do it. Just an 
 academic question.)


 I doubt it'd affect the speed at all. It'd probably make it longer. 
 There are cases in DMD where it seems to make the control flow simpler.


Simpler, yes. Then again, I'd hate to see folks actually start using 
goto in D!!!! If Walter uses it, it's different, he's qualified. :-)



Oh, (for interested readers,) here's the above code in a test bench:

import std.stdio;
void main()
{
     enum {DUMMY};
     int[] X = [DUMMY,2,3,4,19,18,17,5,1,6];
     int n = X.length-1;

     M1: int j=n; int k=n; int m=X[n];
     M2: if(k==0) goto M6;
     M3: if(X[k] <= m) goto M5;
     M4: j=k; m=X[k];
     M5: k--; goto M2;
     M6: ;

     writeln("max: ", m, " pos: ", j);
}

The dummy and length-1 are needed because, in the old days, especially 
text books had arrays 1-based. Also numbering things in general used to 
be 1-based, because "computing culture" hadn't spread to the general 
public yet. You didn't want to explain all over again the merits of zero 
based indexing every time you chalked up an example.

The interesting part is, still today, this algorithm is essentially what 
the computer ends up doing, no matter how "structured" our source code was.

Apr 23 2009

Charles Hixson <charleshixsn earthlink.net> writes:

Georg Wrede wrote:
 Don wrote:
 Georg Wrede wrote:
 Don wrote:
 Georg Wrede wrote:
 Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


 Michael A. Jackson wouldn't approve 1175 gotos in 113 files.


 It'd be really funny to pass it through one of those "code quality" 
 metrics, one of the ones with a ridiculously heavy penalty for using 
 goto. I think it'd tell you that DMD source is almost the 
 lowest-quality code on the planet. <g>


 Yeah. But now I'm getting a bad conscience, this is beginning to look 
 like Walter-bashing... :-)


 I think those code quality metrics are ridiculous. The prejudice 
 against 'goto' is really just brainwashing and totally without basis.


 Well, at the time, they had no choice. Unstructured code was the norm, 
 and people who tangled themselves in spaghetti never noticed it's 
 because of goto usage. Instead they just preceived programming as hard.
 
 The language on my first computer was old fashioned BASIC, with line 
 numbers and no named subroutines or structural elements. I felt that the 
 effort needed to program was exponential to the number of lines. In 
 hindsight, that must have been entirely because I'd had no higher 
 education in programming, no notion of structuring the code (in any 
 particular way), etc. But the absolutely worst thing was that one 
 couldn't pass parameters to subroutines. (gosub <lineNumber>) And all 
 variables were global.
 
 In those days most programming was done in COBOL, by (essentially) 
 non-programmers. (The idea of COBOL was, after all, to be usable by 
 business people, not MSc programmers.) Jackson had to change not only 
 the methodology, but before that, the concept and the motivation for 
 using structured programming. That was the hard part, and it needed some 
 serious evangelising and brainwashing, to overcome the inertia.
 
 Unfortunately, that meant murdering, dismembering, and pulverizing any 
 least hint of even thinking about using goto. And as with any paradigm 
 shift, the disciples took it to religious extremes.
 
 Here's a recent link from Andrew Koenig, who really should know better.

 http://dobbscodetalk.com/index.php?option=com_myblog&show=What-Dijkstra-said-was-harmful-about-goto-state
ents.html&Itemid=29 

 Can you see his fundamental mistake? He talks about "the program" 
 (just as Dijkstra said), but it's just not relevant for 
 C/C++/D/Pascal/...
 or any other structured programming language. Wherever he says 
 "program" you should substitute "function". And then the force of the 
 argument totally disappears.


 Yes.
 
 The problem with goto in an unstructured language is that when you see 
 a label, you don't know where it came from. It could be anywhere in 
 the entire program (maybe a million lines of code!) And that's a 
 complete disaster. But in a structured language, you know it's from 
 somewhere in the function.
 And this is no different from any other control structure. You ALWAYS 
 have to look at the whole scope you're in.

 void foo(){
  int n;
 bool b = true;
   while (b) {
     if (n==4) {   /* when do we get here? You have to read the whole 
 function to find out. Where does n get modified? */ }
 :
 :
 :
   }
 }

 Heck, even in inline ASM in D, you can't write the kind of spaghetti 
 code Dijkstra was complaining about. You always have local scope.


 OTOH, getting the algorithm may become tedious even in small snippets. 
 For example, here's Algorithm M, from /Fundamental Algorithms/, Knuth 
 1969, page 95:
 
     M1: int j=n; int k=n; int m=X[n];
     M2: if(k==0) goto M6;
     M3: if(X[k] <= m) goto M5;
     M4: j=k; m=X[k];
     M5: k--; goto M2;
     M6: ;
 
 That's three gotos for six lines. How long did it take to fully figure 
 out what it's doing? Way longer than if it were written in structured D, 
 anyway.
 
 Yet, I personally have been so affected by anti-goto brainwashing that 
 I've never used goto in C, C++, or D. But I gradually realised that it 
 was just brainwashing. I've never experienced any problem with goto in 
 ASM.


 Same here. Last time I used it was in Pascal, and boy, did I have a bad 
 conscience. It felt like I was doing something Mom has forbidden.
 
 Actually, looking through the DMD source it becomes obvious that 
 goto is really not a problem at all. The lack of comments is much 
 more of a problem. (Especially with files with names like "e2ir.c". 
 What the heck is "fltables.c", "cdxxx.c", "elxxx.c" ?). Even so, 
 it's mostly not that difficult to understand.


 I guess Walter has to keep alternating between ASM, C and D. And a 
 lot of ASM coding is nothing more than a bunch of MOV and JMP stuff. 
 And file naming conventions here look like what one typically finds 
 in development code (before some pre-publishing guy has tidyed it up 
 with a lot of global search&replaces). And, after all, the C files 
 never were meant to be public anyway.

 Actually, the one interesting question might be, would rewriting this 
 code in a structured fashion (I mean, removing the gotos) make it 
 slower? (Not that I'd be suggesting Walter should do it. Just an 
 academic question.)


 I doubt it'd affect the speed at all. It'd probably make it longer. 
 There are cases in DMD where it seems to make the control flow simpler.


 Simpler, yes. Then again, I'd hate to see folks actually start using 
 goto in D!!!! If Walter uses it, it's different, he's qualified. :-)
 
 
 
 Oh, (for interested readers,) here's the above code in a test bench:
 
 import std.stdio;
 void main()
 {
     enum {DUMMY};
     int[] X = [DUMMY,2,3,4,19,18,17,5,1,6];
     int n = X.length-1;
 
     M1: int j=n; int k=n; int m=X[n];
     M2: if(k==0) goto M6;
     M3: if(X[k] <= m) goto M5;
     M4: j=k; m=X[k];
     M5: k--; goto M2;
     M6: ;
 
     writeln("max: ", m, " pos: ", j);
 }
 
 The dummy and length-1 are needed because, in the old days, especially 
 text books had arrays 1-based. Also numbering things in general used to 
 be 1-based, because "computing culture" hadn't spread to the general 
 public yet. You didn't want to explain all over again the merits of zero 
 based indexing every time you chalked up an example.
 
 The interesting part is, still today, this algorithm is essentially what 
 the computer ends up doing, no matter how "structured" our source code was.


Even for it's time Basic was a bad language.  Fortran was much better, 
and it existed before Basic was created.  (Basic was created as a 
"simple version" of Fortran.  The language was, but using it wasn't.)

I still believe, however, that the go to statement should be avoided. 
Even in small routines.  Because they may not stay small.  (Doesn't mean 
you shouldn't ever use it.  Sometimes it may actually simplify AND 
clarify the code.  But very rarely.  I've only found occasion to 
actually use it about four times since structured programming features 
were introduced in the various languages that I use.  Generally it can 
be replaced by a labeled break or continue statement...and even those 
I've rarely needed since I altered my style to accommodate structures. 
The one context I used to use the goto in is now handled by exceptions.

(Yes, one can argue that a labeled break or continue is effectively a 
goto, but it is very different in having much more local context.  It's 
limited to a nest of loops rather than to a function.)

Apr 23 2009

Sean Kelly <sean invisibleduck.org> writes:

Georg Wrede wrote:
 
 Actually, the one interesting question might be, would rewriting this 
 code in a structured fashion (I mean, removing the gotos) make it 
 slower? (Not that I'd be suggesting Walter should do it. Just an 
 academic question.)


Yes.  For better or worse, goto is sometimes the best way to write 
efficient code without any duplication.

Apr 22 2009

Walter Bright <newshound1 digitalmars.com> writes:

Georg Wrede wrote:
 Yeah. But now I'm getting a bad conscience, this is beginning to look 
 like Walter-bashing... :-)


Don't worry, I'm immune to that. Back in 1984 or so during a code review 
at work, a colleague grepped for goto and presented a listing of all the 
gotos with the comment about what a piece of crap my code was.

A lot of what I use goto for Andrei has demonstrated can be replaced 
with scope guards and his enforce template.

Apr 27 2009

Leandro Lucarella <llucax gmail.com> writes:

Don, el 22 de abril a las 09:24 me escribiste:
 Georg Wrede wrote:
Walter Bright wrote:
Lutger wrote:
what the hell...this code can't be human.


I was replaced by Colossus years ago.




 It'd be really funny to pass it through one of those "code quality"
 metrics, one of the ones with a ridiculously heavy penalty for using
 goto. I think it'd tell you that DMD source is almost the lowest-quality
 code on the planet. <g>


Try the Linux kernel.

The difference is:
a) Well, Linux is a kernel =)
b) Gotos are not used gratuitously in the kernel code, they are used to
   handle error, which is almost the only right way to do it in C. For
   what I saw for the DMD code that's not true.

-- 
Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/
----------------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145  104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------------
1950 we were 3 billion people on the earth,
today we are 6 billion people

Apr 22 2009

Walter Bright <newshound1 digitalmars.com> writes:

Don wrote:
 Actually, looking through the DMD source it becomes obvious that goto is 
 really not a problem at all. The lack of comments is much more of a 
 problem. (Especially with files with names like "e2ir.c".


e2ir => Expression To Intermediate Representation


 What the heck 
 is "fltables.c", "cdxxx.c", "elxxx.c" ?). Even so, it's mostly not that 
 difficult to understand.


Those are generated by optabgen.exe.

Apr 27 2009

Walter Bright <newshound1 digitalmars.com> writes:

Georg Wrede wrote:
 Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


 Michael A. Jackson wouldn't approve 1175 gotos in 113 files.



I see I was being too obscure.
See "Colossus, the Forbin Project" http://us.imdb.com/title/tt0064177/

Apr 27 2009

Christopher Wright <dhasenan gmail.com> writes:

Walter Bright wrote:
 Georg Wrede wrote:
 Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


 Michael A. Jackson wouldn't approve 1175 gotos in 113 files.


 
 I see I was being too obscure.
 See "Colossus, the Forbin Project" http://us.imdb.com/title/tt0064177/


To clarify: you are *not* 80 feet high and protector of Rhodes?

Apr 27 2009

Georg Wrede <georg.wrede iki.fi> writes:

Walter Bright wrote:
 Georg Wrede wrote:
 Walter Bright wrote:
 Lutger wrote:
 what the hell...this code can't be human.


 I was replaced by Colossus years ago.


 Michael A. Jackson wouldn't approve 1175 gotos in 113 files.


 I see I was being too obscure.
 See "Colossus, the Forbin Project" http://us.imdb.com/title/tt0064177/


Heh, by an incredible coincidence, it aired here a couple of weeks ago. 
Maybe that's why I felt the reference too obvious to comment on.

I liked the end. Not what I expected. And more thought provoking like 
this. It also gave some new depth about understanding the Terminator.

Apr 28 2009

Walter Bright <newshound1 digitalmars.com> writes:

Georg Wrede wrote:
 Walter Bright wrote:
 I see I was being too obscure.
 See "Colossus, the Forbin Project" http://us.imdb.com/title/tt0064177/


 Heh, by an incredible coincidence, it aired here a couple of weeks ago. 
 Maybe that's why I felt the reference too obvious to comment on.


I think it is an overlooked classic.

Apr 28 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Lars T. Kyllingstad wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary 
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 This is looking very nice! I want to switch from D1 to D2, but...
 
 I don't want to sound greedy or anything, and I know others have asked 
 for this before, but is making a 64-bit Linux version of DMD a lot of work?


I would kill for a 64-bit Linux DMD. I think it could take a lot of ways 
of coding to a whole new level. Sean and I have also been discussing how 
to integrate memory-mapped files with the garbage collector. In a 64-bit 
environment this makes for an awesome programming model.


Andrei

Apr 21 2009

"Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:

Andrei Alexandrescu wrote:
 Lars T. Kyllingstad wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary 
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 This is looking very nice! I want to switch from D1 to D2, but...

 I don't want to sound greedy or anything, and I know others have asked 
 for this before, but is making a 64-bit Linux version of DMD a lot of 
 work?


 I would kill for a 64-bit Linux DMD. [...]


Who does one have to kill to get a 64-bit compiler around here? :)

But seriously, now that the language itself is stabilising, I would 
consider this a major priority for further development of DMD. 64 bits 
is the (immediate) future.

-Lars

Apr 21 2009

Leandro Lucarella <llucax gmail.com> writes:

Andrei Alexandrescu, el 21 de abril a las 07:38 me escribiste:
 Lars T. Kyllingstad wrote:
Walter Bright wrote:
This is a major revision to Phobos, including Andrei's revolutionary new range 
support.

http://www.digitalmars.com/d/2.0/changelog.html
http://ftp.digitalmars.com/dmd.2.029.zip


I don't want to sound greedy or anything, and I know others have asked for this 
before, but is making a 64-bit Linux version of DMD a lot of work?


 I would kill for a 64-bit Linux DMD. I think it could take a lot of ways of 
 coding to a whole new level. Sean and I have also been discussing how to 
 integrate memory-mapped files with the garbage collector. In a 64-bit 
 environment this makes for an awesome programming model.


Can you elaborate on that?

Thanks.

-- 
Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/
----------------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145  104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------------

Apr 21 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Leandro Lucarella wrote:
 Andrei Alexandrescu, el 21 de abril a las 07:38 me escribiste:
 Lars T. Kyllingstad wrote:
 Walter Bright wrote:
 This is a major revision to Phobos, including Andrei's revolutionary new range 
 support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 I don't want to sound greedy or anything, and I know others have asked for
this 
 before, but is making a 64-bit Linux version of DMD a lot of work?


 coding to a whole new level. Sean and I have also been discussing how to 
 integrate memory-mapped files with the garbage collector. In a 64-bit 
 environment this makes for an awesome programming model.


 Can you elaborate on that?


Not much time, but in short: Memory-mapped files are not a pure library 
thing, they are core because they manipulate the address space. So they 
are quite like memory allocation. Unmapping files by hand is as unsafe 
as calling delete. So memory mapped files must be integrated with the 
collector: you map a file by hand, and the garbage collector closes it 
when there are no more references to the memory mapped for the file.

The programming model is pretty cool - in 32 bit I always need to mind 
the address space because it's so densely populated. In 64 bits I can 
map all of my data files in memory and let the paging system and the 
garbage collector take care of the rest.


Andrei

Apr 21 2009

Lutger <lutger.blijdestijn gmail.com> writes:

Walter Bright wrote:

 
 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.
 
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Thanks so much, looking good!

The lambda template parameters: very cool.

Apr 21 2009

Don <nospam nospam.com> writes:

Walter Bright wrote:
 
 This is a major revision to Phobos, including Andrei's revolutionary new 
 range support.
 
 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Missing from the changelog:

 From 2.208:
2804 Impure nested functions should be legal inside pure functions

 From 2.209:
std.math:
Intrinsics std.math.yl2x and yl2xp1 added. Improves performance of 
std.math.log() and similar functions (and they are now pure nothrow).

(Yes, I know, not very exciting compared to Andrei's new Phobos <g>).

Apr 21 2009

bearophile <bearophileHUGS lycos.com> writes:

Don:
  From 2.208:
 2804 Impure nested functions should be legal inside pure functions


Very good. Now that little example works:

import std.c.stdio: printf;
import std.conv: to;

pure int double_sqr(int x) {
    int y, z;
    void do_sqr() { y *= y; }
    y = x;
    do_sqr();
    z += y;
    y = x;
    do_sqr();
    z += y;
    return z;
}

void main(string[] args) {
    int x = args.length == 2 ? to!(int)(args[1]) : 10;
    int y = double_sqr(x) + double_sqr(x);
    printf("4 * x * x = %d\n", y);
}

The outout is correct:
4 * x * x = 400


"Cleaned up" ASM produced by DMD V.2.029, -O -release -inline:

double_sqr:
        push    EAX
        mov ECX,EAX
        mov [ESP],0
        mov [ESP],ECX
        imul    EAX,[ESP]
        mov EDX,EAX
        mov [ESP],EAX
        mov EAX,ECX
        mov [ESP],ECX
        imul    EAX,[ESP]
        add EDX,EAX
        mov [ESP],EAX
        mov EAX,EDX
        pop ECX
        ret

double_sqr.do_sqr:
        mov ECX,[EAX]
        imul    ECX,[EAX]
        mov [EAX],ECX
        ret

main:
L0:     sub ESP,014h
        cmp dword ptr 018h[ESP],2
        jne L21
        mov EDX,01Ch[ESP]
        mov EAX,018h[ESP]
        mov EAX,8[EDX]
        mov EDX,0Ch[EDX]
        push    EDX
        push    EAX
        call    near ptr parseString
        jmp short   L26
L21:        mov EAX,0Ah
L26:        call    near ptr double_sqr
        add EAX,EAX
        mov ECX,offset FLAT:_DATA
        push    EAX
        push    ECX
        call    near ptr printf

As you can see there's only one call to double_sqr in the main program, so the
pure semantics is working here.

You can also see do_sqr is inlined into double_sqr. But the asm code inside
double_sqr looks very hairy and long, and double_sqr itself isn't inlined in
the main.

Bye,
bearophile

Apr 21 2009

bearophile <bearophileHUGS lycos.com> writes:

I have tried the following code:

import std.c.stdio: printf;
import std.conv: to;

nothrow pure int double_sqr(int x) { // line 4
    int y, z;
    nothrow void do_sqr() { y *= y; }
    y = x;
    do_sqr();
    z += y;
    y = x;
    do_sqr();
    z += y;
    return z;
}

void main(string[] args) {
    int x = args.length == 2 ? to!(int)(args[1]) : 10;
    int y = double_sqr(x) + double_sqr(x);
    printf("4 * x * x = %d\n", y);
}

The compiler spits the following error:

pure_impure_test.d(4): Error: function pure_impure_test.double_sqr 'double_sqr'
is nothrow yet may throw

but I don't understand why. What are the things inside it that can throw an
exception?

Bye,
bearophile

Apr 21 2009

bearophile <bearophileHUGS lycos.com> writes:

I have also tested the semantics of nested function purity:

import std.c.stdio: printf;
import std.conv: to;

pure int double_sqr(int x) {
    pure int sqr(int y) { return y * y; }
    return sqr(x) + sqr(x);
}

void main(string[] args) {
    int x = args.length == 2 ? to!(int)(args[1]) : 10;
    int y = double_sqr(x) + double_sqr(x);
    printf("4 * x * x = %d\n", y);
}

Compiled without inlining:
-O -release

double_sqr.sqr:
        mov EAX,4[ESP]
        imul    EAX,EAX
        ret 4

double_sqr:
L0:     push    EAX
        push    EAX
        xor EAX,EAX
        call    near ptr double_sqr.sqr
        push    EAX
        sub ESP,4
        xor EAX,EAX
        push    dword ptr 8[ESP]
        call    near ptr double_sqr.sqr
        add ESP,4
        mov ECX,EAX
        pop EAX
        add EAX,ECX
        pop ECX
        ret

main:
L0:     push    EAX
        cmp dword ptr 8[ESP],2
        jne L1D
        mov EDX,0Ch[ESP]
        mov EAX,8[ESP]
        push    dword ptr 0Ch[EDX]
        push    dword ptr 8[EDX]
        call    near ptr to!(int)()
        jmp short   L22
L1D:        mov EAX,0Ah
L22:        call    near ptr double_sqr
        add EAX,EAX
        mov ECX,offset FLAT:_DATA
        push    EAX
        push    ECX
        call    near ptr printf

There's one call to double_sqr but unfortunately two to double_sqr.sqr.

Bye,
bearophile

Apr 21 2009

Don <nospam nospam.com> writes:

bearophile wrote:
 I have also tested the semantics of nested function purity:
 
 import std.c.stdio: printf;
 import std.conv: to;
 
 pure int double_sqr(int x) {
     pure int sqr(int y) { return y * y; }
     return sqr(x) + sqr(x);
 }
 
 void main(string[] args) {
     int x = args.length == 2 ? to!(int)(args[1]) : 10;
     int y = double_sqr(x) + double_sqr(x);
     printf("4 * x * x = %d\n", y);
 }
 
 Compiled without inlining:
 -O -release
 
 double_sqr.sqr:
         mov EAX,4[ESP]
         imul    EAX,EAX
         ret 4
 
 double_sqr:
 L0:     push    EAX
         push    EAX
         xor EAX,EAX
         call    near ptr double_sqr.sqr
         push    EAX
         sub ESP,4
         xor EAX,EAX
         push    dword ptr 8[ESP]
         call    near ptr double_sqr.sqr
         add ESP,4
         mov ECX,EAX
         pop EAX
         add EAX,ECX
         pop ECX
         ret
 
 main:
 L0:     push    EAX
         cmp dword ptr 8[ESP],2
         jne L1D
         mov EDX,0Ch[ESP]
         mov EAX,8[ESP]
         push    dword ptr 0Ch[EDX]
         push    dword ptr 8[EDX]
         call    near ptr to!(int)()
         jmp short   L22
 L1D:        mov EAX,0Ah
 L22:        call    near ptr double_sqr
         add EAX,EAX
         mov ECX,offset FLAT:_DATA
         push    EAX
         push    ECX
         call    near ptr printf
 
 There's one call to double_sqr but unfortunately two to double_sqr.sqr.
 
 Bye,
 bearophile


Yes. Actually, marking a nested function as pure doesn't make much sense.
It's entirely equivalent to moving it outside the function; a nested 
pure function shouldn't be able to access any members of the enclosing 
function, otherwise it's not pure. But DMD doesn't enforce that, and so 
it creates inefficient and possibly buggy code.

I'm not sure that nested pure member functions should be legal.

Apr 21 2009

Don <nospam nospam.com> writes:

Don wrote:
 bearophile wrote:
 I have also tested the semantics of nested function purity:

 import std.c.stdio: printf;
 import std.conv: to;

 pure int double_sqr(int x) {
     pure int sqr(int y) { return y * y; }
     return sqr(x) + sqr(x);
 }

 void main(string[] args) {
     int x = args.length == 2 ? to!(int)(args[1]) : 10;
     int y = double_sqr(x) + double_sqr(x);
     printf("4 * x * x = %d\n", y);
 }

 Compiled without inlining:
 -O -release

 double_sqr.sqr:
         mov EAX,4[ESP]
         imul    EAX,EAX
         ret 4

 double_sqr:
 L0:     push    EAX
         push    EAX
         xor EAX,EAX
         call    near ptr double_sqr.sqr
         push    EAX
         sub ESP,4
         xor EAX,EAX
         push    dword ptr 8[ESP]
         call    near ptr double_sqr.sqr
         add ESP,4
         mov ECX,EAX
         pop EAX
         add EAX,ECX
         pop ECX
         ret

 main:
 L0:     push    EAX
         cmp dword ptr 8[ESP],2
         jne L1D
         mov EDX,0Ch[ESP]
         mov EAX,8[ESP]
         push    dword ptr 0Ch[EDX]
         push    dword ptr 8[EDX]
         call    near ptr to!(int)()
         jmp short   L22
 L1D:        mov EAX,0Ah
 L22:        call    near ptr double_sqr
         add EAX,EAX
         mov ECX,offset FLAT:_DATA
         push    EAX
         push    ECX
         call    near ptr printf

 There's one call to double_sqr but unfortunately two to double_sqr.sqr.

 Bye,
 bearophile


 Yes. Actually, marking a nested function as pure doesn't make much sense.
 It's entirely equivalent to moving it outside the function; a nested 
 pure function shouldn't be able to access any members of the enclosing 
 function, otherwise it's not pure. But DMD doesn't enforce that, and so 
 it creates inefficient and possibly buggy code.


The bug is bugzilla 2807.

 I'm not sure that nested pure member functions should be legal.


And it turns out that sqr() isn't actually pure, in the same way that it 
wasn't nothrow in your first example. The 'pure' marker is silently 
being ignored. If you put the 'pure' at the end, you get bug 2807.

--

Apr 21 2009

bearophile <bearophileHUGS lycos.com> writes:

Don:
 Yes. Actually, marking a nested function as pure doesn't make much sense.
 It's entirely equivalent to moving it outside the function; [...]
 I'm not sure that nested pure member functions should be legal.


It's not fully equivalent to moving it out of the function because once you
pull it out you add a name to the outer namespace: nested functions are useful
to keep namespaces tidy too.
So I'd like to have nested pure functions too.

pure int foo(int y) { return y + y; } // outer foo
pure void bar(int x) {
  pure int foo(int y) { return y * y; }
  return foo(x) * .foo(x);
}

Thank you,
bye,
bearophile

Apr 21 2009

Don <nospam nospam.com> writes:

bearophile wrote:
 Don:
 Yes. Actually, marking a nested function as pure doesn't make much sense.
 It's entirely equivalent to moving it outside the function; [...]
 I'm not sure that nested pure member functions should be legal.


 It's not fully equivalent to moving it out of the function because once you
pull it out you add a name to the outer namespace: nested functions are useful
to keep namespaces tidy too.
 So I'd like to have nested pure functions too.
 
 pure int foo(int y) { return y + y; } // outer foo
 pure void bar(int x) {
   pure int foo(int y) { return y * y; }
   return foo(x) * .foo(x);
 }
 
 Thank you,
 bye,
 bearophile


That's true, but it seems quite difficult to get right. A pure nested 
function can in theory access immutable members in the outer function -- 
but must not access the parameters of the outer function.
If there are no immutable members in the outer function, the compiler 
would ideally convert it into an external pure function, so that it
doesn't need a frame pointer to the outer function. But it would need 
error messages for any use of mutable outer function members. Etc.
It seems quite a lot of work for something of very limited use.
Making it into a external, private pure function is almost the same.

Apr 21 2009

Don <nospam nospam.com> writes:

Don wrote:
 bearophile wrote:
 Don:
 Yes. Actually, marking a nested function as pure doesn't make much 
 sense.
 It's entirely equivalent to moving it outside the function; [...]
 I'm not sure that nested pure member functions should be legal.


 It's not fully equivalent to moving it out of the function because 
 once you pull it out you add a name to the outer namespace: nested 
 functions are useful to keep namespaces tidy too.
 So I'd like to have nested pure functions too.

 pure int foo(int y) { return y + y; } // outer foo
 pure void bar(int x) {
   pure int foo(int y) { return y * y; }
   return foo(x) * .foo(x);
 }

 Thank you,
 bye,
 bearophile


 That's true, but it seems quite difficult to get right. A pure nested 
 function can in theory access immutable members in the outer function -- 
 but must not access the parameters of the outer function.
 If there are no immutable members in the outer function, the compiler 
 would ideally convert it into an external pure function, so that it
 doesn't need a frame pointer to the outer function. But it would need 
 error messages for any use of mutable outer function members. Etc.
 It seems quite a lot of work for something of very limited use.
 Making it into a external, private pure function is almost the same.
 
 


it's only 5 lines long! It gives an error message if a nested pure 
function accesses a mutable variable from an outer scope.

Apr 22 2009

bearophile <bearophileHUGS lycos.com> writes:

Don:
 Actually it's not so difficult. I've created a patch for bug 2807 -- 
 it's only 5 lines long! It gives an error message if a nested pure 
 function accesses a mutable variable from an outer scope.


Thank you very much Don, your work helps a lot.

Every time I try a tiny program I find something I don't understand:

import std.stdio: writeln;
import std.math: sqrt;
import std.conv: to;

void main(string[] args) {
    double x = args.length == 2 ? to!(double)(args[1]) : 4.0;
    writeln(sqrt(x) + sqrt(x));
}

I have also tried with std.math.sin with similar results:

L0:		enter	8,0
		mov	EAX,8[EBP]
		cmp	EAX,2
		jne	L30
		cmp	EAX,1
		ja	L1B
		mov	EAX,6
		call	near ptr _D6test7__arrayZ
L1B:		mov	EDX,0Ch[EBP]
		mov	EAX,8[EBP]
		mov	EAX,8[EDX]
		mov	EDX,0Ch[EDX]
		push	EDX
		push	EAX
		call	near ptr _D3std4conv13__T2toTdTAyaZ2toFAyaZd
		jmp short	L36
L30:		fld	qword ptr FLAT:_DATA[00h]
L36:		fstp	qword ptr -8[EBP]
		fld	qword ptr -8[EBP]
		fsin
		fld	qword ptr -8[EBP]
		fsin
		faddp	ST(1),ST
		sub	ESP,0Ch
		fstp	tbyte ptr [ESP]
		call	near ptr _D3std5stdio14__T7writelnTeZ7writelnFeZv
		xor	EAX,EAX
		leave
		ret

Isn't sin(x)+sin(x) pure? Even if the compiler doesn't want to replace x+x with
x*2 because x is a floating point, it can do:

y = sin(x)
y+y

And that gives the same result even with FPs.

Note: with SSE2 it's even possible to perform two sqrt(double) at the same
time, so a compiler can implement sin(x)+sin(y) with a single instruction
(SQRTSD) (plus eventually some register loading/unloading).

Bye,
bearophile

Apr 22 2009

bearophile <bearophileHUGS lycos.com> writes:

bearophile:
 so a compiler can implement sin(x)+sin(y) with a single instruction (SQRTSD)


I meant sqrt(x)+sqrt(y), sorry.

Apr 22 2009

Don <nospam nospam.com> writes:

bearophile wrote:
 Don:
 Actually it's not so difficult. I've created a patch for bug 2807 -- 
 it's only 5 lines long! It gives an error message if a nested pure 
 function accesses a mutable variable from an outer scope.


 Thank you very much Don, your work helps a lot.
 
 Every time I try a tiny program I find something I don't understand:
 
 import std.stdio: writeln;
 import std.math: sqrt;
 import std.conv: to;
 
 void main(string[] args) {
     double x = args.length == 2 ? to!(double)(args[1]) : 4.0;
     writeln(sqrt(x) + sqrt(x));
 }
 
 I have also tried with std.math.sin with similar results:
 
 L0:		enter	8,0
 		mov	EAX,8[EBP]
 		cmp	EAX,2
 		jne	L30
 		cmp	EAX,1
 		ja	L1B
 		mov	EAX,6
 		call	near ptr _D6test7__arrayZ
 L1B:		mov	EDX,0Ch[EBP]
 		mov	EAX,8[EBP]
 		mov	EAX,8[EDX]
 		mov	EDX,0Ch[EDX]
 		push	EDX
 		push	EAX
 		call	near ptr _D3std4conv13__T2toTdTAyaZ2toFAyaZd
 		jmp short	L36
 L30:		fld	qword ptr FLAT:_DATA[00h]
 L36:		fstp	qword ptr -8[EBP]
 		fld	qword ptr -8[EBP]
 		fsin
 		fld	qword ptr -8[EBP]
 		fsin
 		faddp	ST(1),ST
 		sub	ESP,0Ch
 		fstp	tbyte ptr [ESP]
 		call	near ptr _D3std5stdio14__T7writelnTeZ7writelnFeZv
 		xor	EAX,EAX
 		leave
 		ret
 
 Isn't sin(x)+sin(x) pure? Even if the compiler doesn't want to replace x+x
with x*2 because x is a floating point, it can do:
 
 y = sin(x)
 y+y
 
 And that gives the same result even with FPs.


Yes. From further investigation, I've found that:
(1) the optimisation of pure only happens for int returns, not for 
floating-point return types. It should convert purefunc(x)+purefunc(x) 
into 2*purefunc(x) if the return type of purefunc is int, float, or complex.

(2) the back-end isn't smart enough to convert f*2 into f+f.

It's difficult to work out where it's optimising the int return. I can 
see where it marks pure calls as subexpressions to be potentially 
eliminated: OTae(op) is true in gflow.c(660) if it's a pure call, false 
if it's an impure call.
The problem may simply be that the backend doesn't do much common 
subexpression elimination of floating-point expressions.

I really don't understand the backend. It's quite cryptic. Key acronyms 
are AE, CP and VBE. Then there's Bin, Bgen, Bkill, etc.
AE *might* be Available Expression (but what does that mean?)
CP might be Copy Propagation info
I've found that VBE = "Very Busy Expression"! (what does that mean?)

Fixing your problem is beyond me at present, I think.

Apr 23 2009

bearophile <bearophileHUGS lycos.com> writes:

Don:
 I really don't understand the backend. It's quite cryptic. Key acronyms 
 are AE, CP and VBE. Then there's Bin, Bgen, Bkill, etc.
 AE *might* be Available Expression (but what does that mean?)
 CP might be Copy Propagation info
 I've found that VBE = "Very Busy Expression"! (what does that mean?)


I suggest to add comments to the DMD source code every time a small mystery is
revealed, to rename the files once a much better name is found, to improve and
refactor the code every time it a good thing to do it. Every time you put your
hand in the code you can improve the code locally and leave it better then
before (this is the Scout principle in programming).
Then such patches/changes can be slowly folded back into DMD and with time the
sources will improve and will become more readable. Once they can be understood
better, further changes become faster and simpler.

Bye,
bearophile

Apr 23 2009

Don <nospam nospam.com> writes:

bearophile wrote:
 Don:
 I really don't understand the backend. It's quite cryptic. Key acronyms 
 are AE, CP and VBE. Then there's Bin, Bgen, Bkill, etc.
 AE *might* be Available Expression (but what does that mean?)
 CP might be Copy Propagation info
 I've found that VBE = "Very Busy Expression"! (what does that mean?)


 I suggest to add comments to the DMD source code every time a small mystery is
revealed, to rename the files once a much better name is found, to improve and
refactor the code every time it a good thing to do it. Every time you put your
hand in the code you can improve the code locally and leave it better then
before (this is the Scout principle in programming).
 Then such patches/changes can be slowly folded back into DMD and with time the
sources will improve and will become more readable. Once they can be understood
better, further changes become faster and simpler.


I'd love to do that, but unfortunately it's not easy to get _any_ 
changes into DMD. Only Walter has write-access to it, and AFAIK he 
checks every line and enters it manually. Like Linus was famous for 
doing with the Linux kernel.

 
 Bye,
 bearophile

Apr 23 2009

Don <nospam nospam.com> writes:

Don wrote:
 bearophile wrote:


 Isn't sin(x)+sin(x) pure? Even if the compiler doesn't want to replace 
 x+x with x*2 because x is a floating point, it can do:

 y = sin(x)
 y+y

 And that gives the same result even with FPs.


 Yes. From further investigation, I've found that:
 (1) the optimisation of pure only happens for int returns, not for 
 floating-point return types. It should convert purefunc(x)+purefunc(x) 
 into 2*purefunc(x) if the return type of purefunc is int, float, or 
 complex.
 
 (2) the back-end isn't smart enough to convert f*2 into f+f.


I learnt a lot about the backend in the process, maybe I can fix (1) now.

Apr 25 2009

Michel Fortin <michel.fortin michelf.com> writes:

On 2009-04-21 11:18:39 -0400, Don <nospam nospam.com> said:

 Yes. Actually, marking a nested function as pure doesn't make much sense.
 It's entirely equivalent to moving it outside the function; a nested 
 pure function shouldn't be able to access any members of the enclosing 
 function, otherwise it's not pure. But DMD doesn't enforce that, and so 
 it creates inefficient and possibly buggy code.


What about immutable local variables? A pure function can access 
immutable globals, so it should be able to access immutable locals too.

-- 
Michel Fortin
michel.fortin michelf.com
http://michelf.com/

Apr 21 2009

Daniel Keep <daniel.keep.lists gmail.com> writes:

Michel Fortin wrote:
 On 2009-04-21 11:18:39 -0400, Don <nospam nospam.com> said:
 
 Yes. Actually, marking a nested function as pure doesn't make much sense.
 It's entirely equivalent to moving it outside the function; a nested
 pure function shouldn't be able to access any members of the enclosing
 function, otherwise it's not pure. But DMD doesn't enforce that, and
 so it creates inefficient and possibly buggy code.


 What about immutable local variables? A pure function can access
 immutable globals, so it should be able to access immutable locals too.
 


If you treat the nested function's context pointer as a pointer to a
struct matching the stack layout, then you can have pure nested
functions -- they have exactly the same semantics as a pure struct
member function.

  -- Daniel

Apr 21 2009

Don <nospam nospam.com> writes:

Daniel Keep wrote:
 
 Michel Fortin wrote:
 On 2009-04-21 11:18:39 -0400, Don <nospam nospam.com> said:

 Yes. Actually, marking a nested function as pure doesn't make much sense.
 It's entirely equivalent to moving it outside the function; a nested
 pure function shouldn't be able to access any members of the enclosing
 function, otherwise it's not pure. But DMD doesn't enforce that, and
 so it creates inefficient and possibly buggy code.


 immutable globals, so it should be able to access immutable locals too.


 If you treat the nested function's context pointer as a pointer to a
 struct matching the stack layout, then you can have pure nested
 functions -- they have exactly the same semantics as a pure struct
 member function.
 
   -- Daniel


True, but that would mean that it'd be pretty useless. It's almost 
exactly the same as not marking it pure.
pure foo(int x)
{
   int y;
   pure int bar(int z) { return z*z; }

   int a= bar(2);
   y++;
   int b = bar(2); // has to recalculate bar(2), because y has changed.
}

---
The basic issue is that the situations where marking a nested function 
as 'pure' is a good idea, is extremely limited.
Compared to making it an external pure private function, with any 
desired immutable members passed as parameters, it has these advantages 
and disadvantages.
+ inaccessable to other functions in the same module.
+ can access immutable members in the outer function, without passing 
them as parameters.
- slower, since it needs a context pointer as well as a frame pointer.

I think those benefits are pathetic.

Apr 22 2009

Don <nospam nospam.com> writes:

Steven Schveighoffer wrote:
 On Wed, 22 Apr 2009 03:12:04 -0400, Don <nospam nospam.com> wrote:
 
 Daniel Keep wrote:
  Michel Fortin wrote:
 On 2009-04-21 11:18:39 -0400, Don <nospam nospam.com> said:

 Yes. Actually, marking a nested function as pure doesn't make much 
 sense.
 It's entirely equivalent to moving it outside the function; a nested
 pure function shouldn't be able to access any members of the enclosing
 function, otherwise it's not pure. But DMD doesn't enforce that, and
 so it creates inefficient and possibly buggy code.


 immutable globals, so it should be able to access immutable locals too.


 struct matching the stack layout, then you can have pure nested
 functions -- they have exactly the same semantics as a pure struct
 member function.
    -- Daniel


 True, but that would mean that it'd be pretty useless. It's almost 
 exactly the same as not marking it pure.
 pure foo(int x)
 {
    int y;
    pure int bar(int z) { return z*z; }

    int a= bar(2);
    y++;
    int b = bar(2); // has to recalculate bar(2), because y has changed.
 }

 ---
 The basic issue is that the situations where marking a nested function 
 as 'pure' is a good idea, is extremely limited.
 Compared to making it an external pure private function, with any 
 desired immutable members passed as parameters, it has these 
 advantages and disadvantages.
 + inaccessable to other functions in the same module.
 + can access immutable members in the outer function, without passing 
 them as parameters.
 - slower, since it needs a context pointer as well as a frame pointer.

 I think those benefits are pathetic.


 What about treating nested functions of pure functions like a logical 
 grouping of statements within the function?  That is, when you call a 
 nested function inside a pure function, the call can't be optimized, but 
 any calls the nested function makes (to a global pure function) can be 
 optimized, and the nested function still provides the same guarantees 
 (cannot access any globals, must only call other pure functions), 
 however it can access and modify locals within the outer function.


That's exactly what my recent change (2804) did.

 I use nested functions a lot not as mini functions within a function but 
 as simple ways to avoid duplicating code everywhere in my function.
 
 You probably couldn't allow taking a delegate of such a function either.


I've just submitted a patch (2695) which makes usage of function 
pointers and delegates safe within pure functions. Basically, you can 
take the delegate of a nested function, but you can't call it.
You could return it, but I believe that's OK, because it should become a 
closure.

I'm on a quest to make 'pure' usable in D <g>.

Apr 22 2009

Tomas Lindquist Olsen <tomas.l.olsen gmail.com> writes:

On Thu, Apr 23, 2009 at 2:37 PM, Don <nospam nospam.com> wrote:
 bearophile wrote:
 Don:
 I really don't understand the backend. It's quite cryptic. Key acronyms
 are AE, CP and VBE. Then there's Bin, Bgen, Bkill, etc.
 AE *might* be Available Expression (but what does that mean?)
 CP might be Copy Propagation info
 I've found that VBE = "Very Busy Expression"! (what does that mean?)


 I suggest to add comments to the DMD source code every time a small
 mystery is revealed, to rename the files once a much better name is found,
 to improve and refactor the code every time it a good thing to do it. Every
 time you put your hand in the code you can improve the code locally and
 leave it better then before (this is the Scout principle in programming).
 Then such patches/changes can be slowly folded back into DMD and with time
 the sources will improve and will become more readable. Once they can be
 understood better, further changes become faster and simpler.


 I'd love to do that, but unfortunately it's not easy to get _any_ changes
 into DMD. Only Walter has write-access to it, and AFAIK he checks every line
 and enters it manually. Like Linus was famous for doing with the Linux
 kernel.


Glad to hear I'm not the only one with that impression...

Apr 23 2009

Don <nospam nospam.com> writes:

bearophile wrote:
 I have tried the following code:
 
 import std.c.stdio: printf;
 import std.conv: to;
 
 nothrow pure int double_sqr(int x) { // line 4
     int y, z;
     nothrow void do_sqr() { y *= y; }
     y = x;
     do_sqr();
     z += y;
     y = x;
     do_sqr();
     z += y;
     return z;
 }
 
 void main(string[] args) {
     int x = args.length == 2 ? to!(int)(args[1]) : 10;
     int y = double_sqr(x) + double_sqr(x);
     printf("4 * x * x = %d\n", y);
 }
 
 The compiler spits the following error:
 
 pure_impure_test.d(4): Error: function pure_impure_test.double_sqr
'double_sqr' is nothrow yet may throw
 
 but I don't understand why. What are the things inside it that can throw an
exception?
 
 Bye,
 bearophile


Obviously my 2808 patch only solved one part of the problem.
It compiles if you change do_sqr to
void do_sqr() nothrow { y *= y; }
Please add a bug report to Bugzilla.

Apr 21 2009

Tomas Lindquist Olsen <tomas.l.olsen gmail.com> writes:

On Tue, Apr 21, 2009 at 8:56 PM, Don <nospam nospam.com> wrote:
 bearophile wrote:
 Don:
 Yes. Actually, marking a nested function as pure doesn't make much sens=






 It's entirely equivalent to moving it outside the function; [...]
 I'm not sure that nested pure member functions should be legal.


 It's not fully equivalent to moving it out of the function because once
 you pull it out you add a name to the outer namespace: nested functions =




 useful to keep namespaces tidy too.
 So I'd like to have nested pure functions too.

 pure int foo(int y) { return y + y; } // outer foo
 pure void bar(int x) {
 =C2=A0pure int foo(int y) { return y * y; }
 =C2=A0return foo(x) * .foo(x);
 }

 Thank you,
 bye,
 bearophile


 That's true, but it seems quite difficult to get right. A pure nested
 function can in theory access immutable members in the outer function -- =


 must not access the parameters of the outer function.
 If there are no immutable members in the outer function, the compiler wou=


 ideally convert it into an external pure function, so that it
 doesn't need a frame pointer to the outer function. But it would need err=


 messages for any use of mutable outer function members. Etc.
 It seems quite a lot of work for something of very limited use.
 Making it into a external, private pure function is almost the same.


why not just make it a static pure nested function? or is that no
longer proper D2 ?

Apr 21 2009

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Wed, 22 Apr 2009 03:12:04 -0400, Don <nospam nospam.com> wrote:

 Daniel Keep wrote:
  Michel Fortin wrote:
 On 2009-04-21 11:18:39 -0400, Don <nospam nospam.com> said:

 Yes. Actually, marking a nested function as pure doesn't make much  
 sense.
 It's entirely equivalent to moving it outside the function; a nested
 pure function shouldn't be able to access any members of the enclosing
 function, otherwise it's not pure. But DMD doesn't enforce that, and
 so it creates inefficient and possibly buggy code.


 immutable globals, so it should be able to access immutable locals too.


 struct matching the stack layout, then you can have pure nested
 functions -- they have exactly the same semantics as a pure struct
 member function.
    -- Daniel


 True, but that would mean that it'd be pretty useless. It's almost  
 exactly the same as not marking it pure.
 pure foo(int x)
 {
    int y;
    pure int bar(int z) { return z*z; }

    int a= bar(2);
    y++;
    int b = bar(2); // has to recalculate bar(2), because y has changed.
 }

 ---
 The basic issue is that the situations where marking a nested function  
 as 'pure' is a good idea, is extremely limited.
 Compared to making it an external pure private function, with any  
 desired immutable members passed as parameters, it has these advantages  
 and disadvantages.
 + inaccessable to other functions in the same module.
 + can access immutable members in the outer function, without passing  
 them as parameters.
 - slower, since it needs a context pointer as well as a frame pointer.

 I think those benefits are pathetic.


What about treating nested functions of pure functions like a logical  
grouping of statements within the function?  That is, when you call a  
nested function inside a pure function, the call can't be optimized, but  
any calls the nested function makes (to a global pure function) can be  
optimized, and the nested function still provides the same guarantees  
(cannot access any globals, must only call other pure functions), however  
it can access and modify locals within the outer function.

I use nested functions a lot not as mini functions within a function but  
as simple ways to avoid duplicating code everywhere in my function.

You probably couldn't allow taking a delegate of such a function either.

-Steve

Apr 22 2009

tama <repeatedly gmail.com> writes:

On Mon, 20 Apr 2009 16:09:09 +0900, Walter Bright  
<newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary new  
 range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


Range is so cool!

Though...
I tried following code:

void main()
{
     writeln("Case1");
     {
         Mt19937 gen = Mt19937(0);
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen = Mt19937(0);
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("(J\(BnCase2");
     {
         Mt19937 gen;
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen;
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
}

Result:

Case1
2357136044 (1)
2546248239 (2)
---
2546248239 (2)
3071714933 (3)

Case2
581869302  (1)
3890346734 (2)
---
581869302  (1)?
3890346734 (2)?

I think 'Case1' is correct, but 'Case2' is wrong.
Mt19937's bug?

-- 
tama <repeatedly gmail.com>
http://profile.livedoor.com/repeatedly/
$B%a%s%P!<Jg=8Cf(B
http://tpf.techtalk.jp/

Apr 21 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

tama wrote:
 On Mon, 20 Apr 2009 16:09:09 +0900, Walter Bright 
 <newshound1 digitalmars.com> wrote:
 
 This is a major revision to Phobos, including Andrei's revolutionary 
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Range is so cool!
 
 Though...
 I tried following code:
 
 void main()
 {
     writeln("Case1");
     {
         Mt19937 gen = Mt19937(0);
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen = Mt19937(0);
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("\nCase2");
     {
         Mt19937 gen;
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen;
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
 }
 
 Result:
 
 Case1
 2357136044 (1)
 2546248239 (2)
 ---
 2546248239 (2)
 3071714933 (3)
 
 Case2
 581869302  (1)
 3890346734 (2)
 ---
 581869302  (1)?
 3890346734 (2)?
 
 I think 'Case1' is correct, but 'Case2' is wrong.
 Mt19937's bug?
 


If you initialize the Mersenne twister with no seed it will start with
seed 5489u.

Andrei

Apr 22 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Steven Schveighoffer wrote:
 On Wed, 22 Apr 2009 13:49:18 -0400, Andrei Alexandrescu 
 <SeeWebsiteForEmail erdani.org> wrote:
 
 tama wrote:
 On Mon, 20 Apr 2009 16:09:09 +0900, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Range is so cool!

 Though...
 I tried following code:

 void main()
 {
     writeln("Case1");
     {
         Mt19937 gen = Mt19937(0);
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen = Mt19937(0);
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("\nCase2");
     {
         Mt19937 gen;
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen;
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
 }

 Result:

 Case1
 2357136044 (1)
 2546248239 (2)
 ---
 2546248239 (2)
 3071714933 (3)

 Case2
 581869302  (1)
 3890346734 (2)
 ---
 581869302  (1)?
 3890346734 (2)?

 I think 'Case1' is correct, but 'Case2' is wrong.
 Mt19937's bug?


 If you initialize the Mersenne twister with no seed it will start with
 seed 5489u.


 I think his point is in the second part of Case2, he skipped one 
 element, but it appears that it didn't skip anything.


Oh ok, thanks tama and Steve. I know where the problem is (on the 
Mersenne twister, if you call popFront without ever calling head there's 
a bug). Could you submit a bug? I'm on battery and on short time, and 
Walter is bugging me :o).


Andrei

Apr 22 2009

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

Masahiro Nakagawa wrote:
 I submitted this problem to bugzilla.
 http://d.puremagic.com/issues/show_bug.cgi?id=2882


Thanks! I fixed it and checked in std.random.

Andrei

Apr 23 2009

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Wed, 22 Apr 2009 13:49:18 -0400, Andrei Alexandrescu  
<SeeWebsiteForEmail erdani.org> wrote:

 tama wrote:
 On Mon, 20 Apr 2009 16:09:09 +0900, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Range is so cool!

 Though...
 I tried following code:

 void main()
 {
     writeln("Case1");
     {
         Mt19937 gen = Mt19937(0);
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen = Mt19937(0);
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("\nCase2");
     {
         Mt19937 gen;
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen;
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
 }

 Result:

 Case1
 2357136044 (1)
 2546248239 (2)
 ---
 2546248239 (2)
 3071714933 (3)

 Case2
 581869302  (1)
 3890346734 (2)
 ---
 581869302  (1)?
 3890346734 (2)?

 I think 'Case1' is correct, but 'Case2' is wrong.
 Mt19937's bug?


 If you initialize the Mersenne twister with no seed it will start with
 seed 5489u.


I think his point is in the second part of Case2, he skipped one element,  
but it appears that it didn't skip anything.

-Steve

Apr 22 2009

"Masahiro Nakagawa" <repeatedly gmail.com> writes:

Changed sender name from screen name to real name.

On Thu, 23 Apr 2009 02:55:37 +0900, Steven Schveighoffer  
<schveiguy yahoo.com> wrote:
 On Wed, 22 Apr 2009 13:49:18 -0400, Andrei Alexandrescu  
 <SeeWebsiteForEmail erdani.org> wrote:

 tama wrote:
 On Mon, 20 Apr 2009 16:09:09 +0900, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Range is so cool!

 Though...
 I tried following code:

 void main()
 {
     writeln("Case1");
     {
         Mt19937 gen = Mt19937(0);
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen = Mt19937(0);
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("\nCase2");
     {
         Mt19937 gen;
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen;
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
 }

 Result:

 Case1
 2357136044 (1)
 2546248239 (2)
 ---
 2546248239 (2)
 3071714933 (3)

 Case2
 581869302  (1)
 3890346734 (2)
 ---
 581869302  (1)?
 3890346734 (2)?

 I think 'Case1' is correct, but 'Case2' is wrong.
 Mt19937's bug?


 If you initialize the Mersenne twister with no seed it will start with
 seed 5489u.


 I think his point is in the second part of Case2, he skipped one  
 element, but it appears that it didn't skip anything.


Lack of talk about this problem:|

-- 
tama <repeatedly gmail.com>
http://profile.livedoor.com/repeatedly/

Apr 22 2009

"Masahiro Nakagawa" <repeatedly gmail.com> writes:

On Thu, 23 Apr 2009 03:12:16 +0900, Andrei Alexandrescu  
<SeeWebsiteForEmail erdani.org> wrote:

 Steven Schveighoffer wrote:
 On Wed, 22 Apr 2009 13:49:18 -0400, Andrei Alexandrescu  
 <SeeWebsiteForEmail erdani.org> wrote:

 tama wrote:
 On Mon, 20 Apr 2009 16:09:09 +0900, Walter Bright
 <newshound1 digitalmars.com> wrote:

 This is a major revision to Phobos, including Andrei's revolutionary
 new range support.

 http://www.digitalmars.com/d/2.0/changelog.html
 http://ftp.digitalmars.com/dmd.2.029.zip


 Range is so cool!

 Though...
 I tried following code:

 void main()
 {
     writeln("Case1");
     {
         Mt19937 gen = Mt19937(0);
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen = Mt19937(0);
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("\nCase2");
     {
         Mt19937 gen;
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
     writeln("---");
     {
         Mt19937 gen;
         advance(gen, 1);  // skip 1 element
         writeln(gen.front);
         gen.popFront;
         writeln(gen.front);
     }
 }

 Result:

 Case1
 2357136044 (1)
 2546248239 (2)
 ---
 2546248239 (2)
 3071714933 (3)

 Case2
 581869302  (1)
 3890346734 (2)
 ---
 581869302  (1)?
 3890346734 (2)?

 I think 'Case1' is correct, but 'Case2' is wrong.
 Mt19937's bug?


 If you initialize the Mersenne twister with no seed it will start with
 seed 5489u.


 element, but it appears that it didn't skip anything.


 Oh ok, thanks tama and Steve. I know where the problem is (on the  
 Mersenne twister, if you call popFront without ever calling head there's  
 a bug). Could you submit a bug? I'm on battery and on short time, and  
 Walter is bugging me :o).


http://d.puremagic.com/issues/show_bug.cgi?id=2882

-- 
tama <repeatedly gmail.com>
http://profile.livedoor.com/repeatedly/

Apr 22 2009

"Masahiro Nakagawa" <repeatedly gmail.com> writes:

On Thu, 23 Apr 2009 18:09:06 +0900, Andrei Alexandrescu  
<SeeWebsiteForEmail erdani.org> wrote:

 Masahiro Nakagawa wrote:
 I submitted this problem to bugzilla.
 http://d.puremagic.com/issues/show_bug.cgi?id=2882


 Thanks! I fixed it and checked in std.random.



std.random in svn works fine.

Thanks for your quick response.

-- 
tama <repeatedly gmail.com>
http://profile.livedoor.com/repeatedly/

Apr 23 2009

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