Get class type parameters at compile time

[bearophile]

Philippe Sigaud:

> template TemplateArity(Type)
> {
>     enum T = Type.stringof;
>     mixin("alias " ~ T ~ " U;");
>     static if (is(Type _ == U!Args, Args...))
>         enum TemplateArity = Args.length;
>     else
>         enum TemplateArity = -1;
> }
>
> void main()
> {
>     alias Test!(int, double, string) T;
...
>     assert(TemplateArity!T == 3); // External deduction
> }

Fit to be added to Phobos?

Bye,
bearophile