Check whether a type is a instantiated by a template struct

[Chris Cain]

On Saturday, 11 August 2012 at 18:56:30 UTC, Jakob Ovrum wrote:
> struct S(T) {}
>
> template isS(T : S!U, U) {
>     enum isS = true;
> }
>
> template isS(T) {
>     enum isS = false;
> }
>
> static assert(isS!(S!float));
> static assert(!isS!float);

Same idea, but doing it with just one template and using static 
ifs...

struct S(T) {}

template isS(T) {
     static if(is(T _ : S!U, U))
         enum isS = true;
     else
         enum isS = false;
}

static assert(isS!(S!float));
static assert(!isS!float);