Matching variadic non-type templates

Question

Let\'s say I have two structs, Foo and Bar:

template
struct Foo{};

template
struct Bar{};
         


        

Answer 1

Here is a general C++14 solution that does not rely on manually specialized type traits or extending Foo and Bar.

A template metafunction that obtains a type representing the class template of its argument type:

namespace detail
{
    // Type representing a class template taking any number of non-type template arguments.
    template  class U>
    struct nontype_template {};
}

// If T is an instantiation of a class template U taking non-type template arguments,
// this has a nested typedef "type" that is a detail::nontype_template representing U.
template 
struct nontype_template_of {};

// Partial specializations for all of the builtin integral types.
template