c++templatestype-traitstemplate-templates

How to tell whether two class templates are the same

Say I have a function that has two template template parameters like:

template <template <typename...> C1, template <typename...> C2>
constexpr bool is_same_container() {
    return std::is_same<C1, C2>::value;
}

is_same_container<std::vector, std::vector>();

When I compile, the compiler complains that C1 and C2 needs to be supplied with template arguments.

Is there any way to compare two class templates directly?

std::vector should be the same thing as std::vector. How can I find out?

Solution

  • Sure, just write your own trait.

    template<template<class...> class C1, template<class...> class C2>
struct is_same_template : std::false_type {};

template<template<class...> class C>
struct is_same_template<C,C> : std::true_type {};