implicitly convert function pointers to delegates

[KennyTM~]

Moritz Warning wrote:
> Hi,
> 
> some people discovered that functions can be wrapped into delegates 
> without allocation.
> 
> Here is one out of several similar solutions:
> 
> R delegate(T) toDg(R, T...)(R function(T) fp) {
>     struct dg {
>         R opCall(T t) {
>             return (cast(R function(T)) this) (t);
>         }
>     }
>     R delegate(T) t;
>     t.ptr = fp;
>     t.funcptr = &dg.opCall;
>     return t;
> }
> 
> I would like to ask if we can get this into the language?
> It would make working with delegates and function pointers much more 
> easier when function pointers implicitly convert to delegates when they 
> "have to".

vote++ for implicit conversion. An FP can be *safely* converted to any DGs.

BTW,

   alias float delegate (in float) DG;

   float area (in float radius) {
	float r2 = radius * radius;
	return 3.1415926535 * radius;
   }

   DG x;
   x.ptr = null;
   x.funcptr = &area;
   // writefln(typeof(x.funcptr).stringof); // ensure it's an FP not DG.
   writefln(x(10)); // writes 314.159 without any error.


Why this simpler solution is not used? The function pointer can't touch 
the frame pointer anyway (an FP cannot access stuff outside its scope).