// class examples of using initializer lists and inheritance

#include <iostream>
#include <string>
#include <vector>
#include <sstream>

using namespace std;

// this class need to have an initializer list for the constructor because one
// instance variable is a reference (out) and one is declared to be const (id).
class foo {
public:
    foo(ostream & o, const string & the_id, int n)
        : out(o), id(the_id), y(x - 1), z(x + 1), x(2 * n) {
        // nothing else to do
    }

    void print() const {
        out << "x = " << x << ", y = " << y << ", z = " << z << endl;
    }
private:
    ostream & out;
    const string id;
    int y, x, z;  // y will not be initialized properly because of order
};

// base class for inheritance
class person {
public:
    person(const string & s, const string & n)
        : ssn(s), name(n) {
        // nothing else to do
    }

    const string get_name() const {
        return name;
    }

    // had to declare this function to be virtual to get polymorphic behavior
    virtual string to_string() const {
        ostringstream out;
        out << ssn << ", " << name;
        return out.str();
    }
private:
    string ssn;
    string name;
};

// this is a subclass of person that adds a gpa instance variable
class student : public person {
public:
    student(const string & s, const string & n, double g) 
        : person(s, n), gpa(g) {
        // nothing else to do
    }

    string to_string() const {
        ostringstream out;
        out << person::to_string() << ", " << gpa;
        return out.str();
    }
private:
    double gpa;
};

int main() {
    foo f(cout, "879342782", 42);
    f.print();
    cout << endl;

    person p1("833-28-2938", "John Doe");
    student s1("837-99-2343", "Jane Smith", 3.95);
    cout << p1.to_string() << endl;
    cout << s1.to_string() << endl;
    cout << endl;

    // polymorphism
    person & p2 = s1;
    cout << p2.to_string() << endl;
    cout << endl;

    // example of "slicing" (a BIG problem)
    vector<person> v;
    v.push_back(p1);
    v.push_back(p2);
    for (const person & p : v) {
        cout << p.to_string() << endl;
    }

    return 0;
}