Re: Avoiding __traits(getAttributes, ...) on alias

[Stefan Frijters via Digitalmars-d-learn]

On Friday, 9 May 2014 at 12:19:12 UTC, John Colvin wrote:
On Friday, 9 May 2014 at 11:53:59 UTC, Stefan Frijters wrote:
I've been playing with UDAs a bit and I wanted to find all 
variables with a particular attribute in various modules. I 
thought I had it cracked, until I added a module that contains 
an alias declaration, which makes it choke when trying to 
execute __traits(getAttributes, ...). A small example is shown 
below. Is there any conditional I can insert between the two 
foreach lines to make it detect such an alias declaration, and 
move on to the next derived member? Or should getAttributes 
handle this by just returning no attributes?

import std.traits;

@("testattr") int foo;
alias char[256] MyChar;
@("testattr") int bar;

void main() {
 foreach(e ; __traits(derivedMembers, mixin(__MODULE__)))  {
   foreach( t; __traits(getAttributes, mixin(e)) ){
     pragma(msg, t);
   }
 }
 // testattr
 // test.d(9): Error: first argument is not a symbol
 // test.d(9): Error: invalid foreach aggregate false
 // testattr
}

Any hints would be appreciated!

Kind regards,

Stefan Frijters

You could always do a static if with __traits(compiles, 
__traits(getAttributes, mixin(e))

Thank you for the fast reply; this solves my problem. I actually 
tried this before, but in my actual code instead of the example, 
where I'm deep into backticks and quotes and escaped quotes so I 
probably made a mistake there...