Chain Of Responsibility Design Pattern

Chain Of Responsibility Design Pattern avoid coupling the sender of request to its receiver by giving more than one object a chance to handle the request. Chain the receiving object and pass the request along the chain until an object handles it.

Class Diagram:

Class Diagram of real example:

Source code of real example in c++:

/*
* File:chainOfRes.cpp
* This file is described the Chain Of Responsibility Design Pattern with help of example
* Author: Alpha
* Date: 4 Jan 2021
*/

//Header File
#include<iostream>

//class ATM Handler
class AtmHandler
{

AtmHandler* m_suc;
public:
AtmHandler(AtmHandler* s = nullptr): m_suc(s){}
~AtmHandler(){}
virtual void HandleRequest(int amt);
};
void AtmHandler::HandleRequest(int amt)
{
if(m_suc)
m_suc->HandleRequest(amt);
}

//50 Dollar Handler
class Dollar50Handler: public AtmHandler
{

public:
Dollar50Handler(AtmHandler* s = nullptr): AtmHandler(s){}
~Dollar50Handler(){}
void HandleRequest(int amt);
};
void Dollar50Handler::HandleRequest(int amt)
{
//Handle the request otherwise pass the request
if(amt%50 == 0)
{
std::cout<<"Number of 50 Dollar:"<<amt/50<<std::endl;
std::cout<<"Request is completed so no need to forward it"<<std::endl;
}
else
{
int numberOf50Dollar= amt/50;
std::cout<<"Number of 50 Dollar:"<<numberOf50Dollar<<std::endl;
amt = amt-numberOf50Dollar*50;
AtmHandler::HandleRequest(amt);
}
}

//20 Dollar Handler
class Dollar20Handler: public AtmHandler
{

public:
Dollar20Handler(AtmHandler* s = nullptr): AtmHandler(s){}
~Dollar20Handler(){}
void HandleRequest(int amt);
};
void Dollar20Handler::HandleRequest(int amt)
{
//Handle the request otherwise pass the request
if(amt%20 == 0)
{
std::cout<<"Number of 20 Dollar:"<<amt/20<<std::endl;
std::cout<<"Request is completed so no need to forward it"<<std::endl;
}
else
{
int numberOf20Dollar= amt/20;
std::cout<<"Number of 20 Dollar:"<<numberOf20Dollar<<std::endl;
amt = amt-numberOf20Dollar*20;
AtmHandler::HandleRequest(amt);
}
}

//10 Dollar Handler
class Dollar10Handler: public AtmHandler
{

public:
Dollar10Handler(AtmHandler* s = nullptr): AtmHandler(s){}
~Dollar10Handler(){}
void HandleRequest(int amt);
};
void Dollar10Handler::HandleRequest(int amt)
{
//Handle the request otherwise pass the request
if(amt%10 == 0)
{
std::cout<<"Number of 10 Dollar:"<<amt/10<<std::endl;
std::cout<<"Request is completed so no need to forward it"<<std::endl;
}
else
{
std::cout<<"!!!!!!!!!!!!!!!!!!!Can Not with draw this amout please enter correct amount"<<std::endl;
}
}

int main()
{
std::cout<<"Chain of Responsibility"<<std::endl;
Dollar10Handler* p10 = new Dollar10Handler;
Dollar20Handler* p20 = new Dollar20Handler(p10);
Dollar50Handler* p50 = new Dollar50Handler(p20);
AtmHandler* atm = new AtmHandler(p50);
std::cout<<"Please withdraw 530 Dollar"<<std::endl;
atm->HandleRequest(530);

std::cout<<"Please withdraw 545 Dollar"<<std::endl;
atm->HandleRequest(545);

return 0;
}

Compilation command:

g++ chainOfRes.cpp

Output:

Chain of Responsibility
Please withdraw 530 Dollar
Number of 50 Dollar:10
Number of 20 Dollar:1
Number of 10 Dollar:1
Request is completed so no need to forward it
Please withdraw 545 Dollar
Number of 50 Dollar:10
Number of 20 Dollar:2
!!!!!!!!!!!!!!!!!!!Can Not with draw this amout please enter correct amount