Singletons, alias this and DMD crashing

[Leandro Motta Barros]

Thanks for the comment! I noticed this wouldn't compile, though I
haven't really wondered why so. My email was more about the compiler
bug than about using alias this with singletons.

Anyway, while trying to circumvent the compiler bug, I did this:

import std.stdio;

class SImpl
{
   void foo()
   {
      writeln("foo!");
   }

   private this() { }
}

class S
{
   static @property SImpl instance()
   {
      if (_i is null)
         _i = new SImpl();

      return _i;
   }

   static SImpl _i;

   alias instance this;
}

void main()
{
   S.foo();
}

This works and compiles with DMD 2.062. (I don't like to have
to write this additional code manually, but I'll try to make something
about it :-) )

LMB



On Thu, May 9, 2013 at 7:04 AM, Jacob Carlborg <doob at me.com> wrote:
> On 2013-05-09 11:48, Jacob Carlborg wrote:
>
>> This won't work. You need to be able to overload on static, which you
>> can't. I've tried this with opDispatch.
>
>
> To elaborate. Below is your original with the "foo" method added.
>
>
> class S
> {
>    static @property S instance()
>    {
>       if (_i is null) // #1
>          _i = new S();
>
>       return _i;
>    }
>
>    static S _i;
>
>    alias instance this;  // #2
>
>    void foo () {}
> }
>
> If you try to call it like this: S.foo(), the compiler will complain that
> "foo" need access to "this". The "alias this" won't kick in.
>
> --
> /Jacob Carlborg