A solution to multiple opCasts

[Simen Kjaeraas]

I was thinking of the plans for multiple opCasts today, when inspiration
suddenly struck me. What if opCast saved its return value in a reference
parameter of the appropriate type instead? That way, normal overloading  
rules
would kick in, and you could define as many opCasts as you want. For  
instance:

   struct foo
   {
     someType[] data;

     void opCast(ref int result)
     {
       result = 42;
     }

     void opCast(ref string result)
     {
       result = "Text here";
     }

     void opCast(T)(ref T result)
     {
       result = data;
     }
   }

The compiler would then rewrite as follows:

   foo f;
   void bar(string s){}

   int a = cast(int)f; // becomes int a; f.opCast(a);

   bar(cast(string)f); // becomes string tmp; f.opCast(tmp);

   baz b = cast(baz)f; // becomes baz b; f.opCast(baz)(b);


As we can see, the function call introduces a temporary value, which might  
be
unwanted. Apart from that, I can't see any problems OTOH, but I'm sure  
there are
some. Please do comment.

-- Simen