#include <functional>
#include<map>
#include<string>

class Calc {

private:

    void Naming() {}
    std::map<std::string, std::function <void(Calc*)>> Command_Name;

public:

    Calc() {
        Command_Name["var"] = &Calc::Naming;
    }

    void operator()() {
        Command_Name["var"]();
    }
};

int main() {
    Calc calculater;
    calculater();
    return 0;
}