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digitalmars.D.learn - Errors in specification?

reply "Simen Haugen" <simen.haugen pandavre.com> writes:
This is the property example from http://digitalmars.com/d/1.0/property.html

int a;
int b = 1;
typedef int t = 2;
t c;
t d = cast(t)3;

int.init // is 0
a.init  // is 0
b.init  // is 1 // Well, I get 0
t.init  // is 2 // Well, I get 2
c.init  // is 2 // Well, I get 2
d.init  // is 3 // Well, I get 2

struct Foo
{
    int a;
    int b = 7;
}

Foo.a.init // is 0 // Well, I get 0
Foo.b.init // is 7 // Well, I get 0


And another:

enum E { V };
E.V.stringof; // I get int instead of E.V


And another:

float f = 1.0;
f.init; // This should be 1.0 according to the spec.. It's nan here.
const f2 = 1.0;
f2.init; // still nan... Only typedefs changes the init?

Ditto for other types.


And is it possible to check if a float is nan?
float f2;
f2 is float.nan; // false
f2.init is float.init; // false
float.nan is float.nan; // false...


I'm using dmd 1.028
Jun 12 2008
next sibling parent reply "Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:
"Simen Haugen" <simen.haugen pandavre.com> wrote in message 
news:g2s4uk$2nt7$1 digitalmars.com...
 This is the property example from 
 http://digitalmars.com/d/1.0/property.html

 ...

 Ditto for other types.

The behavior of .init was changed in 1.017. Per-variable .inits now just get the .init of the type. I don't know why the spec hasn't been updated to match.
 And is it possible to check if a float is nan?
 float f2;
 f2 is float.nan; // false
 f2.init is float.init; // false
 float.nan is float.nan; // false...

Either use std.math.isnan/tango.math.IEEE.isNaN, or a somewhat.. funnier looking method: float f2; f2 !<>= f2; // true
Jun 12 2008
parent reply "Simen Haugen" <simen norstat.no> writes:
"Jarrett Billingsley" wrote in message
 Either use std.math.isnan/tango.math.IEEE.isNaN, or a somewhat.. funnier 
 looking method:

 float f2;
 f2 !<>= f2; // true

Thanks a lot If I had checked the expression chapter I would have seen that. I must say that at first I thought wtf! I had no idea what you were doing there: "f2 not lt gt eq f2"?!? Sure is a long strange looking operator.
Jun 13 2008
parent reply "Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:
"Simen Haugen" <simen norstat.no> wrote in message 
news:g2tdtv$e76$1 digitalmars.com...
 "Jarrett Billingsley" wrote in message
 Either use std.math.isnan/tango.math.IEEE.isNaN, or a somewhat.. funnier 
 looking method:

 float f2;
 f2 !<>= f2; // true

Thanks a lot If I had checked the expression chapter I would have seen that. I must say that at first I thought wtf! I had no idea what you were doing there: "f2 not lt gt eq f2"?!? Sure is a long strange looking operator.

Heheh. Well I don't think it actually mentions that that's a possible test for nan, but it just happens to work out because of the semantics of that operator.
Jun 13 2008
parent BCS <ao pathlink.com> writes:
Reply to Jarrett,

 "Simen Haugen" <simen norstat.no> wrote in message
 news:g2tdtv$e76$1 digitalmars.com...
 
 "Jarrett Billingsley" wrote in message
 
 Either use std.math.isnan/tango.math.IEEE.isNaN, or a somewhat..
 funnier looking method:
 
 float f2;
 f2 !<>= f2; // true

If I had checked the expression chapter I would have seen that. I must say that at first I thought wtf! I had no idea what you were doing there: "f2 not lt gt eq f2"?!? Sure is a long strange looking operator.

test for nan, but it just happens to work out because of the semantics of that operator.

It's also the only thing it's useful for. However I would like to see "f1 is f2" do an "incorrect" floating point comparison: (NaN is NaN) == true I was planning on asking for it but Simen beat me to it.
Jun 13 2008
prev sibling parent Gide Nwawudu <gide btinternet.com> writes:
On Thu, 12 Jun 2008 23:37:23 +0200, "Simen Haugen"
<simen.haugen pandavre.com> wrote:

This is the property example from http://digitalmars.com/d/1.0/property.html

int a;
int b = 1;
typedef int t = 2;
t c;
t d = cast(t)3;

int.init // is 0
a.init  // is 0
b.init  // is 1 // Well, I get 0
t.init  // is 2 // Well, I get 2
c.init  // is 2 // Well, I get 2
d.init  // is 3 // Well, I get 2

struct Foo
{
    int a;
    int b = 7;
}

Foo.a.init // is 0 // Well, I get 0
Foo.b.init // is 7 // Well, I get 0
 ...

The .init error in spec is already in bugzilla. http://d.puremagic.com/issues/show_bug.cgi?id=2045 Gide
Jun 16 2008