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digitalmars.D - Template parameter-dependent attributes

reply Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:
So, I wrote this beautiful BigO framework: <400 lines all told, clear 
code, real nice. Then I got this cold shower:

void insertFrontMany(C, R)(C container, R range)
      BigO(complexity!(C.insertFront) * linearTime)
{
    ...
}

My hope being of course that for containers with linear insertion time 
at the front I'll get quadratic, etc. The hitch is:

test.d(377): Error: undefined identifier 'C.insertFront'

So... attributes are currently not allowed to depend on template 
parameters, which is a serious damper on enthusiasm.

Seems to me this is a bug - different instantiations should have 
different attributes etc. Is there any matter of principle making this 
not work?

If this won't work at all, I'll need to resort to expressing complexity 
via traits. Not as nice!


Thanks,

Andrei
Dec 16 2015
next sibling parent reply Daniel N <ufo orbiting.us> writes:
On Wednesday, 16 December 2015 at 17:14:50 UTC, Andrei 
Alexandrescu wrote:

 So... attributes are currently not allowed to depend on 
 template parameters, which is a serious damper on enthusiasm.


Indeed, please see the discussion in:
https://issues.dlang.org/show_bug.cgi?id=10193

/Daniel
Dec 16 2015
parent reply Timon Gehr <timon.gehr gmx.ch> writes:
On 12/16/2015 06:46 PM, Daniel N wrote:

 On Wednesday, 16 December 2015 at 17:14:50 UTC, Andrei Alexandrescu wrote:

 So... attributes are currently not allowed to depend on template
 parameters, which is a serious damper on enthusiasm.


 Indeed, please see the discussion in:
 https://issues.dlang.org/show_bug.cgi?id=10193

 /Daniel


This is a slightly different issue. (The UDA is before the declaration 
there.)
Dec 16 2015
parent ZombineDev <valid_email he.re> writes:
On Wednesday, 16 December 2015 at 18:01:11 UTC, Timon Gehr wrote:

 On 12/16/2015 06:46 PM, Daniel N wrote:

 On Wednesday, 16 December 2015 at 17:14:50 UTC, Andrei 
 Alexandrescu wrote:

 So... attributes are currently not allowed to depend on 
 template
 parameters, which is a serious damper on enthusiasm.


 Indeed, please see the discussion in:
 https://issues.dlang.org/show_bug.cgi?id=10193

 /Daniel


 This is a slightly different issue. (The UDA is before the 
 declaration there.)


I thought that it doesn't matter on which side you put the UDA. 
Just like pure nothow, etc. Why should there be any difference?
Dec 16 2015
prev sibling next sibling parent Timon Gehr <timon.gehr gmx.ch> writes:
On 12/16/2015 06:14 PM, Andrei Alexandrescu wrote:

 So, I wrote this beautiful BigO framework: <400 lines all told, clear
 code, real nice. Then I got this cold shower:

 void insertFrontMany(C, R)(C container, R range)
       BigO(complexity!(C.insertFront) * linearTime)
 {
     ...
 }

 My hope being of course that for containers with linear insertion time
 at the front I'll get quadratic, etc.


linear and quadratic in what?


 The hitch is:

 test.d(377): Error: undefined identifier 'C.insertFront'

 So... attributes are currently not allowed to depend on template
 parameters,


Yes, they are.

template bar(T){  (T.str) auto bar(T t){ } }

struct A{ enum str="str"; }
static assert(__traits(getAttributes,bar!A)[0]=="str");



 ...

 Seems to me this is a bug - different instantiations should have
 different attributes etc. Is there any matter of principle making this
 not work?
 ...


No, just a broken lowering in the parser.

auto bar(T)(T t) (T.str){ }

should be the same as

template bar(T){ auto bar(T t) (T.str){ } }

It's probably very easy to fix.
Dec 16 2015
prev sibling next sibling parent reply Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:
On 12/16/2015 12:14 PM, Andrei Alexandrescu wrote:
[snip]

I submitted https://issues.dlang.org/show_bug.cgi?id=15464, which is 
preapproved. There is a bit of a sense of urgency to it - it blocks the 
bigo library proposal and an article.

Takers?


Andrei
Dec 21 2015
next sibling parent Daniel Kozak <kozzi11 gmail.com> writes:
On Monday, 21 December 2015 at 13:58:53 UTC, Andrei Alexandrescu 
wrote:

 On 12/16/2015 12:14 PM, Andrei Alexandrescu wrote:
 [snip]

 I submitted https://issues.dlang.org/show_bug.cgi?id=15464, 
 which is preapproved. There is a bit of a sense of urgency to 
 it - it blocks the bigo library proposal and an article.

 Takers?


 Andrei


https://github.com/D-Programming-Language/dmd/pull/5314
Dec 22 2015
prev sibling parent reply deadalnix <deadalnix gmail.com> writes:
On Monday, 21 December 2015 at 13:58:53 UTC, Andrei Alexandrescu 
wrote:

 On 12/16/2015 12:14 PM, Andrei Alexandrescu wrote:
 [snip]

 I submitted https://issues.dlang.org/show_bug.cgi?id=15464, 
 which is preapproved. There is a bit of a sense of urgency to 
 it - it blocks the bigo library proposal and an article.

 Takers?


 Andrei


I think this is a bit pushed out of the door. What if I want to 
'attribute' the template itself ?
Dec 24 2015
parent reply Xiaoxi <xiaoxi 163.com> writes:
On Thursday, 24 December 2015 at 12:45:12 UTC, deadalnix wrote:

 On Monday, 21 December 2015 at 13:58:53 UTC, Andrei 
 Alexandrescu wrote:

 On 12/16/2015 12:14 PM, Andrei Alexandrescu wrote:
 [snip]

 I submitted https://issues.dlang.org/show_bug.cgi?id=15464, 
 which is preapproved. There is a bit of a sense of urgency to 
 it - it blocks the bigo library proposal and an article.

 Takers?


 Andrei


 I think this is a bit pushed out of the door. What if I want to 
 'attribute' the template itself ?


prefix binds to template.
Dec 24 2015
parent deadalnix <deadalnix gmail.com> writes:
On Thursday, 24 December 2015 at 13:23:51 UTC, Xiaoxi wrote:

 prefix binds to template.


And implcit function arguments ?
Dec 24 2015
prev sibling next sibling parent Manu via Digitalmars-d <digitalmars-d puremagic.com> writes:
On 17 December 2015 at 03:14, Andrei Alexandrescu via Digitalmars-d
<digitalmars-d puremagic.com> wrote:

 So, I wrote this beautiful BigO framework: <400 lines all told, clear code,
 real nice. Then I got this cold shower:

 void insertFrontMany(C, R)(C container, R range)
      BigO(complexity!(C.insertFront) * linearTime)
 {
    ...
 }

 My hope being of course that for containers with linear insertion time at
 the front I'll get quadratic, etc. The hitch is:

 test.d(377): Error: undefined identifier 'C.insertFront'

 So... attributes are currently not allowed to depend on template parameters,
 which is a serious damper on enthusiasm.


Remember that time I complained about this more than 2 and a half years ago?

https://issues.dlang.org/show_bug.cgi?id=10193


 Seems to me this is a bug - different instantiations should have different
 attributes etc. Is there any matter of principle making this not work?


Seems like a bug to me too, since you can express it with a fully
expanded template, just not with the template syntax you actually use.
Dec 23 2015
prev sibling parent deadalnix <deadalnix gmail.com> writes:
On Wednesday, 16 December 2015 at 17:14:50 UTC, Andrei 
Alexandrescu wrote:

 So, I wrote this beautiful BigO framework: <400 lines all told, 
 clear code, real nice. Then I got this cold shower:

 void insertFrontMany(C, R)(C container, R range)
      BigO(complexity!(C.insertFront) * linearTime)
 {
    ...
 }

 My hope being of course that for containers with linear 
 insertion time at the front I'll get quadratic, etc. The hitch 
 is:

 test.d(377): Error: undefined identifier 'C.insertFront'

 So... attributes are currently not allowed to depend on 
 template parameters, which is a serious damper on enthusiasm.

 Seems to me this is a bug - different instantiations should 
 have different attributes etc. Is there any matter of principle 
 making this not work?

 If this won't work at all, I'll need to resort to expressing 
 complexity via traits. Not as nice!


 Thanks,

 Andrei


What you are asking the compiler here is ambiguous. It is not 
clear if the attribute apply to the template (in which case 
argument may not be used) or the instantiated eponymous function 
in it.
Dec 24 2015