Templates and Functions

[Regan Heath]

Oliver wrote:
> Hi,
> 
> I'd like to hand over a function to a template. However I am unable to get access to the functions argument type. In the following code the function's argument has been set to double but it should actually be of type T2. T2 is this case is an array and i would like something to give me the type of the array which i can then use to replace the double with. 
> 
> Any suggestions on how to do this? Thanks a lot.
> 
> -------
> import std.stdio;
> import std.math;
> 
> T1 [] dMap( T1, T2 )( T1 function(double) fp, T2 array) {
>         T1 newArray[];
>         newArray.length = array.length;
>         for(int i = 0; i < array.length; i++) {
>             newArray[i] = fp(array[i]);
>         };
>         return newArray;
> }
> 
> void main() {
>         auto b = [0., 6.5, 3.1415];
>         real function(double a) fp; 
>         fp = function(double a) { return sin(a);} ;
>         auto d = dMap(fp,b);
>         writefln("d = ", d);
> }
> 

I figured you'd use this:

T1 [] dMap( T1, T2:T2[] )( T1 function(T2) fp, T2[] array) {

But that gives:

template dbl.dMap(T1,T2 : T2[]) specialization not allowed for deduced 
parameter T2

and I have no idea why specialization is not allowed :(

Regan