template specialization for arrays

[Timon Gehr]

On 10/30/2011 01:34 AM, J Arrizza wrote:
> Thank you Timon,  I very much appreciate your (and others) help.
>
> I will look all this up in the online docs and the book.
>
> There is still some very odd things in how these fit together. For
> example, if I comment out the last 3 function templates, I get all
> "simpleparms", which is expected.
>
> But if I add in the fourth, I get a compilation error saying the call to
> abc(arr2) is ambiguous. So even though the first one specifies "U =
> void" and "size_t N = 0", and the fourth specifies something very
> different, there is ambiguity between them.
>
> Adding in the third resolves the ambiguity between the first and fourth.
> John
>

I cannot reproduce that behaviour. If I comment out the second and the 
third, I get 3 "simpleparm"s and 1 "static array"

> On Sat, Oct 29, 2011 at 4:02 PM, Timon Gehr <timon.gehr at gmx.ch
> <mailto:timon.gehr at gmx.ch>> wrote:
>
>
>     This works:
>
>     void abc(T, U=void, size_t N=0) (T parm1) {
>         writeln("simpleparm: ", parm1);
>     }
>
>     void abc(T: string) (T parm1) {
>         writeln("string : ", parm1);
>     }
>
>     void abc(T:U[], U) (T parm1) if (isDynamicArray!T) {
>         writeln("dynamic array : ", parm1);
>       }
>
>     void abc(T:U[N], U, size_t N) (T parm1) {
>         writeln("static array : ", parm1);
>
>     }
>
>     void main(string[] args) {
>         abc(1);
>         abc("str");
>         int[] arr = [1, 2];
>         abc(arr);
>         int[2] arr2 =[3, 4];
>         abc(arr2);
>     }
>
>

Whoops, just noticed that I accidentally left the if(isDynamicArray!T) 
in there. That is not necessary, if the pattern matches it will always 
evaluate to true.

void abc(T, U=void, size_t N=0) (T parm1) {
     writeln("simpleparm: ", parm1);
}

//void abc(T: string) (T parm1) {
//    writeln("string : ", parm1);
//}

//void abc(T:U[], U) (T parm1){ // no constraint necessary
//    writeln("dynamic array : ", parm1);
//}

void abc(T:U[N], U, size_t N) (T parm1) {
     writeln("static array : ", parm1);
}

void main(string[] args) {
     abc(1);              // simpleparm
     abc("str");          // simpleparm
     int[] arr = [1, 2];
     abc(arr);            // simpleparm
     int[2] arr2 =[3, 4];
     abc(arr2);           // static array
}

What compiler version are you using?