Static opDispatch

[Steven Schveighoffer]

On Sat, 01 Oct 2011 12:34:50 -0400, Jacob Carlborg <doob at me.com> wrote:

> Have a look at the following code:
>
> class Foo
> {
>      static Foo instance_;
>
>      static Foo instance ()
>      {
>          if (instance_)
>              return instance_;
>
>          return instance_ = new Foo;
>      }
>
>      static auto opDispatch (string name, Args...) (Args args)
>      {
>          mixin("return instance." ~ name ~ "(args);");
>      }
>
>      void bar () {}
> }
>
> void main ()
> {
>      Foo.bar;
> }
>
> Compiling the above code results in:
>
> Error: need 'this' to access member bar
>
> Is it possible somehow to make the above code compile?

It's an issue with namespace polution.  Both instances and the type share  
the same namespace.  It's really a bad limitation IMO.  I have a bug  
report that helps try and separate it:  
http://d.puremagic.com/issues/show_bug.cgi?id=6579

It should work if you use a different class as the singleton:

class Foo2
{
    void bar () {}
}

class Foo
{
       static Foo2 instance_;

       static Foo2 instance ()
       {
           if (instance_)
               return instance_;

           return instance_ = new Foo;
       }

       static auto opDispatch (string name, Args...) (Args args)
       {
           mixin("return instance." ~ name ~ "(args);");
       }

}

-Steve