template_specialization_more_params.cpp

// Fun with templates, showing that a specialization
// can have more parameters than the primary template

#include <iostream>

// primary template
template <typename T>
struct Foo {
    Foo() { std::cout << "Foo<T>\n"; }
};

// partial specialization with more arguments than the primary template
template <typename R, typename... Params>
struct Foo<R(Params...)> {
    Foo() { std::cout << "Foo<R(Params...)>\n"; }
};

int main() {
    int n = 0;
    void func();
    Foo<decltype(func)>();
    Foo<decltype(n)>();
}