Is it possible to check if a type is an instance of a template?

[Andrej Mitrovic]

I can do this:

struct Foo(T) { }
template bar(T : Foo!int) { }

I can check if T is a specific instantiation of Foo. But I want to
check whether T is *any* instantiation of Foo. Is this possible to do?

Otherwise I'm currently having to hardcode via:

template bar(T) if (isOneOf!(T, Foo!int, Foo!double)) { }

But having to list all possible instantiations doesn't really scale too well.