Template function overload for type containing a type

Question

I'm trying to do the following:

#include <iostream>
#include <vector>
#include <tuple>
#include <list>

template <typename T>
void f(T t) {
    std::cout << "1" << std::endl;
}

template <typename T, typename V>
void f(T<std::tuple<V>> t) {
    std::cout << "2" << std::endl;
}

int main() {
    f(std::list<double>{}); // should use first template
    f(std::vector<std::tuple<int>>{}); // should use second template
}

What is the simplest way to do this in C++14? I thought that I could sort of pattern match in this way but the compiler won't have it.

Answer 1

The template parameter T is used as a template-name, so it should be declared as template template parameter. e.g.

template <template <typename...> class T, typename V>
//        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
void f(T<std::tuple<V>> t) {
    std::cout << "2" << std::endl;
}

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