Basic class parametrization example

class_parametrization.cpp

#include <iostream>

template<typename T, typename S>
struct Citizen
{
    Citizen(T k, S l) : k_{k}, l_{l} {}
    T k_;
    S l_;
};

template<typename T>
using Adult = Citizen<T, int>;

template<typename T>
using Teenager = Citizen<T, double>;

template<typename T>
using Sheriff = Citizen<T, char>;

template<typename T>
struct Citizen<T, char>
{
    Citizen(T k, char l) : k_{k}, l_{l} {
        std::cout
            << "### O szeryf, szeryf, ty trzymaj sie\n"
            << "###  Tak bardzo dobrze nie jest, ale nie jest zle\n";
    }
    T k_;
    char l_;
};

int main()
{
    Adult<std::string> a("adult", 10);
    Teenager<double> b(3.14, 2.72);
    Sheriff<double> c(3.14, 'a');
    std::cout << a.k_ << " " << a.l_ << "\n";
    std::cout << b.k_ << " " << b.l_ << "\n";
    std::cout << c.k_ << " " << c.l_ << "\n";
}