Template specialization

[Darrell Gallion via Digitalmars-d-learn]

On Friday, 22 January 2016 at 11:23:56 UTC, Marc Schütz wrote:
> On Friday, 22 January 2016 at 01:33:42 UTC, Darrell Gallion 
> wrote:
>> void foo(A)()
>>         if (!is (A == int)) {
>>     pragma(msg, "int");
>> }
>>
>> void foo(A)()
>>         if (is (A == int[])) {
>>     pragma(msg, "int[]");
>> }
>>
>> void main() {
>>
>>   foo!(int)();
>>   foo!(int[])();
>> }
>>
>> ===========
>>
>> source\app.d(15): Error: template app.foo cannot deduce 
>> function from argument types !(int)(), candidates are:
>> source\app.d(3):        app.foo(A)() if (!is(A == int))
>> source\app.d(8):        app.foo(A)() if (is(A == int[]))
>> source\app.d(16): Error: app.foo called with argument types () 
>> matches both:
>> source\app.d(3):     app.foo!(int[]).foo()
>> and:
>> source\app.d(8):     app.foo!(int[]).foo()
>
> Have a look at the first template constraint. It checks whether 
> the template parameter _is not_ `int`, so of course, the first 
> instantiation fails, and the second one is ambiguous.

I'm aware this doesn't look right or compile.
How do I do this?


void foo(int x)
{ }

void foo(int [] x)
{ }

template foo(T)(T x){}

void main() {
   int x;
   int [] a;
   foo((x);
   foo(a);
   foo("hi");
}