main.cpp

// classes example
#include <iostream>
using namespace std;


class Object {
    public:
        virtual string toString()=0;
        virtual int toInt()=0;
        virtual Object* add(Object* other)=0;
};

class Int : public Object {
    int val;
    public:
        static Int* create(int val) {
            Int *ret = new Int(val);
            return ret;
        }
        Int(int in_val) {
            val = in_val;
        }
        string toString() {
            return std::to_string(val);
        }
        int toInt() {
            return val;
        }
        Object* add(Object* other) {
            int other_val = other->toInt();
            return new Int(this->val + other_val);
        }
};

class String : public Object {
    string val;

    public: 
        static String* create(string val) {
            String* ret = new String(val);
            return ret;
        }
        String(string in_val) {
            val = in_val;
        }
        string toString() {
            return val;
        }
        int toInt() {
            throw "cant cast string to int";
        }
        Object* add(Object* other) {
            return new String(val + (other->toString()));
        }
};


int main () {
    try {
        Object* a = Int::create(2);
        Object* b = String::create("hello");
        Object* c = Int::create(5);
        Object* d = a->add(c);
        cout << "a->toString() " << a->toString() << '\n';
        cout << "b->toString() " << b->toString() << '\n';
        cout << "c->toString() " << c->toString() << '\n';
        cout << "d->toString() " << d->toString() << '\n';
    } catch (const char *msg) {
        cout << "errored with " << msg;
    }
    return 0;
}