Accepting delegates/functions in templates

[Ali Çehreli]

On 05/27/2013 07:05 AM, "Luís Marques" <luismarques at gmail.com>" wrote:

 > If I changed that example to use isSomeFunction it works correctly. But
 > when I tried to use isSomeFunction in the proper context it fails to
 > compile:

It is a red herring. The code fails to compile even without isSomeFunction.

import std.traits;

 >      class A
 >      {
 >          void foo(alias dg)()
 >              if(isSomeFunction!dg)
 >          {
 >          }
 >      }
 >
 >      void main()
 >      {
 >          int x;
 >          A a = new A;
 >          a.foo!((int param) { x = 4;});
 >
 >          // error: cannot use local '__lambda1' as parameter to 
non-global
 >                        template foo(alias dg)() if (isSomeFunction!(dg))
 >      }
 >
 > Can anyone help me understand this?

It is an unsolved technical issue about delegates' currently not having 
sufficient number of context pointers:

   http://d.puremagic.com/issues/show_bug.cgi?id=5710

Ali