Demonstrate the operator hidden problem and solution

assignment-operator-hidden.cpp

#include "stdafx.h"
#include <iostream>

using namespace std;


/**
 * operator= is generated implicitly by compiler, and derived class will hide ones from base class.
 * If you want to use base class's operator=, there are 2 solutions.
 *
 * A common usage to reuse operator= in derived class should be using tempplate parameter as argument type:
 * http://stackoverflow.com/questions/4122214/why-operator-doesnt-get-inherited-from-a-template-class
 *
 */
class Base
{
public:
	Base& operator = (Base* p)
	{
		cout << "Base& operator = (Base* p)" << endl;
		return *this;
	}
};

/**
 * By default, derived class hide base class's operator=;
 */
class Derived0: public Base
{
};


/**
 * The first solution is introduce the base class operator= to derived class by "using".
 * But this way it will introduce all operator= from base class with different argument types:
 *		operator = (Base* p)
 *		operator = (const Base& base)
 */
class Derived1: public Base
{
public:
	using Base::operator=;
};

/**
 * The second solution is define operator= explictly in the derived class, then delegate to base class 
 * implmentation.
 *
 * This is a cleaner one without namespace pollution. And should also work well with muliple inheritance
 * as you can reuse operator= from all base classes.
 */
class Derived2: public Base
{
public:
	Derived2 operator = (Base* p)
	{
		Base::operator=(p);
		return *this;
	}
};

int main()
{
	// Derived0
	Derived0 d0;
	//d0 = new Base();

	// Derived1
	Derived1 d1;
	d1 = new Base();
	d1 = Base();

	// Derived2
	Derived2 d2;
	d2 = new Base();
	//d2 = Base();
	
}