Re: How to assign a delegate to a var ?

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On Monday, 2 June 2014 at 22:18:39 UTC, bioinfornatics wrote:
Hi,
I would like store the delegate to another var but when i try i
get:


testTraitsWithDelegate.d(13): Error: expression template
__lambda2 is void and has no value

I do not want to run it only to save the «function» somewhere.


----------- CODE ------------
import std.stdio;
import std.typecons : Tuple;

struct attribute( alias Pred )
{
     alias Predicate = Pred;
}



struct Data
{
     @attribute!( (a) => a == 42 )
     int x;
}



void main()
{

     bool delegate( int ) tmp;

     pragma( msg, __traits(getAttributes, Data.x)[0].Predicate( 
42
) );

     tmp = __traits(getAttributes, Data.x)[0].Predicate;
}
----------- END CODE ------------

The problem is that you're missing the type of a in "(a) => a == 
42". Without the type, it's actually a template lambda, not a 
lambda function. Try changing it to "(int a) => a == 42".
auto