www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - traits compiles does not work for symbols from other modules

reply Andre Pany <andre s-e-a-p.de> writes:
Hi,

I want to validate whether a class contains a specific attribute. 
I have the attribute name as compile time string. This string 
could either be a direct attribute of the class or a hierarchy 
(TextSettings.Font.Size).

As example T is the class Label and p.name contains the text 
"TextSettings.Font.Size".
TextSettings and Font are again classes.

mixin(`static if (__traits(compiles, 
`~fullyQualifiedName!T~`.`~p.name~`)) {...}

__traits(compiles, ...) only works for symbols of the same 
module, but not for symbols contained in other modules. I reduced 
it to this example coding:

m1.d
-----------------
module m1;

import m2;

class Foo
{
	int foo;
}

void main()
{
	static assert(__traits(compiles, m1.Foo.foo));
	static assert(__traits(compiles, m2.Bar.bar));
}

m2.d
---------------
module m2;

class Bar
{
	int bar;
}

Why does the second assert throws? What can I use instead of 
__traits(compiles,...) ?

Kind regards
André
Jul 24 2017
parent reply ag0aep6g <anonymous example.com> writes:
On 07/24/2017 11:40 PM, Andre Pany wrote:

 m1.d
 -----------------
 module m1;
 
 import m2;
 
 class Foo
 {
      int foo;
 }
 
 void main()
 {
      static assert(__traits(compiles, m1.Foo.foo));
      static assert(__traits(compiles, m2.Bar.bar));
 }
 
 m2.d
 ---------------
 module m2;
 
 class Bar
 {
      int bar;
 }
 
 Why does the second assert throws? What can I use instead of 
 __traits(compiles,...) ?


Works for me. What compiler are you using?
Jul 25 2017
parent reply Andre Pany <andre s-e-a-p.de> writes:
On Tuesday, 25 July 2017 at 08:30:43 UTC, ag0aep6g wrote:

 Works for me. What compiler are you using?


I reduced the example too lot. The issue is occuring if there is 
also a package.d is involved.

m1.d
-----------------------

module m1;

import sub; // Does not throw if replaced with: import sub.m2;

class Foo
{
	int foo;
}

void main()
{
	static assert(__traits(compiles, m1.Foo.foo));
	mixin(`static assert(__traits(compiles, sub.m2.Bar.bar));`);
}

sub/m2.d
----------------------

module sub.m2;

class Bar
{
	int bar;
}

sub/package.d
----------------------

module sub;

public import sub.m2;


I use DMD master (as I already need the static foreach) on 
windows 10.
DMD32 D Compiler v2.075.0-rc1-master-af3eacf


 dmd -run m1.d sub/package.d sub/m2.d




Kind regards
André
Jul 25 2017
parent Andre Pany <andre s-e-a-p.de> writes:
On Tuesday, 25 July 2017 at 11:34:23 UTC, Andre Pany wrote:

 On Tuesday, 25 July 2017 at 08:30:43 UTC, ag0aep6g wrote:

 Works for me. What compiler are you using?


 I reduced the example too lot. The issue is occuring if there 
 is also a package.d is involved.

 m1.d
 -----------------------

 module m1;

 import sub; // Does not throw if replaced with: import sub.m2;

 class Foo
 {
 	int foo;
 }

 void main()
 {
 	static assert(__traits(compiles, m1.Foo.foo));
 	mixin(`static assert(__traits(compiles, sub.m2.Bar.bar));`);
 }

 sub/m2.d
 ----------------------

 module sub.m2;

 class Bar
 {
 	int bar;
 }

 sub/package.d
 ----------------------

 module sub;

 public import sub.m2;


 I use DMD master (as I already need the static foreach) on 
 windows 10.
 DMD32 D Compiler v2.075.0-rc1-master-af3eacf


 [...]




 Kind regards
 André


Issue created: https://issues.dlang.org/show_bug.cgi?id=17683

Is there a known workaround?

Kind regards
André
Jul 25 2017