Example 18-1: Observer Implemented

TOC

• Customer
• Observer
• AddrVerification
• WelcomeLetter

#pragma once
#include 
#include 
#include "Observer.h"
using namespace std;

class Customer
{
public:
	Customer(void);
	
	void attach( Observer *myObserver);
	void detach( Observer *myObserver);
	string* getState();
	void notifyObs();
private:
	vector myObs;
public:
	~Customer(void);
};

#include "Customer.h"

Customer::Customer(void)
{
}

Customer::~Customer(void)
{
}

void Customer::attach( Observer *myObserver)
{
	myObs.push_back( myObserver);
}

void Customer::detach( Observer *myObserver)
{
	for (int i= 0; i< myObs.size(); i++)
	{
		if (myObs[i]== myObserver)
		{
			myObs.erase(myObs.begin()+i);
			return;
		}
	}
}

void Customer::notifyObs()
{
	// set arg to something that helps
	// tell the Observers what happened
	for (int i= 0; i< myObs.size(); i++)
	{
		myObs[i]->update(this);
	}
}

string* Customer::getState()
{
	string *state= new string;

	// set state

	return 0l;
}

#pragma once
class Customer;

class Observer
{
public:
	Observer(void);
	virtual void update( Customer *myCust)= 0;
public:
	~Observer(void);
};

#include "Observer.h"

Observer::Observer(void)
{
}

Observer::~Observer(void)
{
}

#pragma once
#include "Observer.h"
#include "Customer.h"

class AddrVerification : public Observer
{
public:
	AddrVerification(void);
	void update( Customer *myCust);
public:
	~AddrVerification(void);
};

#include "AddrVerification.h"

AddrVerification::AddrVerification(void)
{
}

AddrVerification::~AddrVerification(void)
{
}

void AddrVerification::update ( Customer *myCust) 
{
      // do Address verification stuff here
      // can get more information about customer
      // in question by using myCust
}

#pragma once
#include "Observer.h"
#include "Customer.h"

class WelcomeLetter : public Observer
{
public:
	WelcomeLetter(void);
	void update( Customer *myCust);
public:
	~WelcomeLetter(void);
};

#include "WelcomeLetter.h"

WelcomeLetter::WelcomeLetter(void)
{
}

WelcomeLetter::~WelcomeLetter(void)
{
}

void WelcomeLetter::update( Customer *myCust)
{
   // do Welcome Letter stuff 
   // here can get more 
   // information about customer 
   // in question by using myCust
}