aaaaaaaaaaaaaaaaaaaaa

operator.cpp

#include <iostream>

using namespace std;

class Base {
 public:
    Base() {}
    virtual ~Base() = 0;
    ostream& print(ostream &o) const {
        o << "id: " << id << "\n";
        return o;
    }

 protected:
    int id;
};
Base::~Base() {}

class Derived: public Base {
 public:
    Derived() {}
    Derived(int i) {
        Base::id = i, id2 = 123;
    }
    ~Derived(){}
    ostream& print(ostream &o) const {
        o << "id2: " << id2 << "\n";
        return o;
    }
 private:
    int id2;
};

class Derived2: public Base {
 public:
    Derived2() {}
    ~Derived2() {}
    ostream& print(ostream &o) const {
        o << "name = " << name << "\n";
        return o;
    }
 private:
    string name = "Another type from another class to print";
};

ostream &operator<<(ostream &o, Base *d) {
    d->print(o);
    if (Derived *b = dynamic_cast<Derived *>(d)) {
        return b->print(o);
    }
    if (Derived2 *b = dynamic_cast<Derived2 *>(d)) {
        return b->print(o);
    }
    return o;
}

int main() {
    Base *b = new Derived(20);
    Base *c = new Derived2();

    cout << b;
    cout << "--\n";
    cout << c;

    delete b;
    delete c;

    return 0;
}