Template member function pointer to non-template member function pointer

Question

I have a class with a template method and would like to store its specializations in a container. My question is whether it's valid to cast the specialized template method pointer to a non-template method pointer of the same class that shares the same signature. Consider:

#include <iostream>
#include <string>
#include <unordered_map>

using namespace std;

struct S {
    using Method = void(S::*)();

    template <typename T>
    void method1() {
        cout << "method1(): " << T() << endl;
    }

    template <typename T, typename U>
    void method2() { 
        cout << "method2(): " << T() << ", " << U() << endl;
    }

    void call(string name)
    {
        auto method_pair = methods.find(name);
        if (method_pair == methods.end()) {
            cout << name << " not found" << endl;
            return;
        }

        Method& method = method_pair->second;
        (this->*method)();
    }

    unordered_map<string, Method> methods;
};

int main()
{
    S s;

    s.methods["method_int"] = &S::method1<int>;
    s.methods["method_bool"] = &S::method1<bool>;
    s.methods["method_int_int"] = &S::method2<int, int>;
    s.methods["method_bool_int"] = &S::method2<bool, int>;

    cout << boolalpha;
    s.call("method_int");
    s.call("method_bool");
    s.call("method_int_int");
    s.call("method_bool_int");
    s.call("nonexistant");

    return 0;
}

Output:

method1(): 0
method1(): false
method2(): 0, 0
method2(): false, 0
nonexistant not found

The above code compiles and runs just fine with no warnings on my setup. I'm pretty new to C++ member function pointers and I've read that casting them can be dangerous so that's why I'm asking.

Thanks in advance.

Answer 1

After you instantiate a template method with distinct types it gets all the properties of a regular method: it becomes a distinct function with an address, name (that includes the types you used for instantiation), etc. So your approach is valid.