tried different ways of registering classes, but the simple and stupid is the only reliable way

register classes.cpp

#include <iostream>
using namespace std;

class x {
public:
    virtual const char* symbol(void) { return "x"; }
    virtual void speak() { cout << "'x' says 'your mom'" << endl; }
private:
    static char* sym;
};

class a : public virtual x {
public:
    a() { };
    virtual void speak() { cout << "'" << symbol() << "' says 'moo'" << endl; }
    virtual const char* symbol(void) { return "a"; }
private:
    static char* sym;
};

class b : public virtual x {
public:
    b() { };
    virtual void speak() { cout << "'" << symbol() << "' says 'boo'" << endl; }
    virtual const char* symbol(void) { return "b"; }
private:
    static char* sym;
};

class c : public virtual x {
public:
    c() { };
    virtual void speak() { cout << "'" << symbol() << "' says 'foo'" << endl; }
    virtual const char* symbol(void) { return "c"; }
private:
    static char* sym;
};

class symbol_table {
public:
    static void reg(x* obj) {
        string symbol = obj->symbol();
        cout << symbol << " registered." << endl;
        obj->speak();
    }
    static void load(void) {
        reg(new a());
        reg(new b());
        reg(new c());
    }
};

int main(void) {
    symbol_table::load();
}