static-polymorphism.cpp

#include <iostream>

using Age = unsigned int;
using Name = std::string;
using Country = std::string;

template <class PersonSubtype>
class Person
{
public:
    Person(Age age_, Name name_, Country country_)
    : age(age_)
    , name(name_)
    , country(country_) {}
    Age age;
    Name name;
    Country country;

    bool from_south_america() {
        return this->country == "Brazil";
    }

    bool from_sao_paulo() {
        return static_cast<PersonSubtype*>(this)->from_sao_paulo();
    }

    void dump() {
        std::cout << this->name << " is " << (this->from_south_america() ? "" : "not ")
                << "South American and comes from " << (this->from_sao_paulo() ? "Sao Paulo" : "elsewhere")
                << std::endl;
    }
};


struct Brazilian : public Person<Brazilian>
{
    using Person<Brazilian>::Person;
    bool from_sao_paulo() {
        return true;
    }
};

struct Lithuanian : public Person<Lithuanian>
{
    using Person<Lithuanian>::Person;
    bool from_sao_paulo() {
        return false;
    }
};

int main() {
    Brazilian ricardo(30, "Ricardo", "Brazil");
    Lithuanian egle(24, "Egle", "Lithuania");
    ricardo.dump();
    egle.dump();
    return 0;
}