template instantiation --- having trouble therewith

[John Colvin]

On Tuesday, 3 September 2013 at 03:49:52 UTC, Carl Sturtivant 
wrote:
>
> template Dptr( T, U...) {
> 	alias T delegate( U args) Dptr;
> }
>
> Dptr!(T,U) muddle( T, U...)( Dptr!(T,U) f) {
> 	return f; //or make another delegate in real code
> }
>
>
> unittest {
> 	import std.stdio;
> 	int x = 3;
> 	int scale( int s) { return x * s; }
> 	Dptr!(int,int) f = muddle( &scale);
> 	writeln( f(7));
> }
> ============================================
>
> The above technique seemed natural to me, but I get this 
> message from dmd:
>
> p1.d(15): Error: template p1.muddle does not match any function 
> template declaration. Candidates are:
> p1.d(7):        p1.muddle(T, U...)(Dptr!(T, U) f)
> p1.d(15): Error: template p1.muddle(T, U...)(Dptr!(T, U) f) 
> cannot deduce template function from argument types !()(int 
> delegate(int))
>
> and if I use muddle!(int,int) instead it doesn't help. This is 
> likely a misunderstanding on my part --- please show me how to 
> sort this out.

I'm confused as to what you're trying to do... your example code 
is equivalent to

   import std.stdio;
   int x = 3;
   int scale( int s) { return x * s; }
   auto f = &scale;
   writeln( f(7) );