Builder Design pattern Example

Builder Design pattern Description

Builder Design pattern Example Source code in c++:

/*
* File:builder.cpp
* This file is described the builder Design Pattern with help of example
* Author: Aplha
* Date: 29 Dec 2020
*/

//Header File
#include<iostream>

//Engine
class Engine
{
int m_Power;
public:
void setPower(int pw) { m_Power = pw; }
int getPower(){ return m_Power;}
};

//Body
class Body
{
int m_BodySize;
public:
void setBody(int sz) { m_BodySize = sz; }
int getBody() { return m_BodySize;}
};

//Wheel
class Wheel
{
int m_WheelSize;
public:
void setWheel(int sz) { m_WheelSize = sz; }
int getWheel() { return m_WheelSize;}
};

//Car Class
class Car
{
//Data member MUST BE PRIVATE but here I am using as public for demo example
public:
Engine m_eng;
Body m_body;
Wheel m_wh;
public:

};

//HyundaiCarBuilder
class IHyundaiCarBuilder
{
protected:
Car* m_car;
public:
virtual void BuildEngine() = 0;
virtual void BuildBody() = 0;
virtual void BuildWheel() = 0;
virtual Car GetCar() = 0;
};

//Car_i10Builder
class Car_i10Builder: public IHyundaiCarBuilder
{
public:
Car_i10Builder()
{ m_car = new Car; }
~Car_i10Builder() { delete m_car;}
void BuildEngine(){ m_car->m_eng.setPower(1000);}
void BuildBody(){ m_car->m_body.setBody(100);}
void BuildWheel(){m_car->m_wh.setWheel(10);}
Car GetCar()
{
std::cout<<"Car i10 is ready"<<std::endl;
return (*m_car);
}
};

//Car_i20Builder
class Car_i20Builder: public IHyundaiCarBuilder
{
public:
Car_i20Builder()
{ m_car = new Car; }
~Car_i20Builder() { delete m_car;}
void BuildEngine(){ m_car->m_eng.setPower(2000);}
void BuildBody(){ m_car->m_body.setBody(200);}
void BuildWheel(){m_car->m_wh.setWheel(20);}
Car GetCar()
{
std::cout<<"Car i20 is ready"<<std::endl;
return (*m_car);
}
};

//Director
class Director
{
IHyundaiCarBuilder* m_builder;
public:
Director(IHyundaiCarBuilder* build): m_builder(build) {}
void SetBuilder(IHyundaiCarBuilder* build)
{
m_builder = build;
}
void Construct()
{
m_builder->BuildEngine();
m_builder->BuildBody();
m_builder->BuildWheel();
}
};

//Client
int main()
{
std::cout<<"Builder Design Pattern"<<std::endl;
std::cout<<"Using i10 Builder for building i10"<<std::endl;
IHyundaiCarBuilder* build = new Car_i10Builder;
Director* dir = new Director(build);
dir->Construct();
Car car = build->GetCar();
std::cout<<"Engine Power:"<<car.m_eng.getPower()<<std::endl;
std::cout<<"Body Size:"<<car.m_body.getBody()<<std::endl;
std::cout<<"Wheel Size:"<<car.m_wh.getWheel()<<std::endl;
delete build;

std::cout<<"Using i20 Builder for building i20"<<std::endl;
IHyundaiCarBuilder* buildi20 = new Car_i20Builder;
dir->SetBuilder(buildi20);
dir->Construct();
car = build->GetCar();
std::cout<<"Engine Power:"<<car.m_eng.getPower()<<std::endl;
std::cout<<"Body Size:"<<car.m_body.getBody()<<std::endl;
std::cout<<"Wheel Size:"<<car.m_wh.getWheel()<<std::endl;
delete buildi20;
delete dir;
return 0;
}

Compilation command:

g++ -std=c++11 builder.cpp

Output:

Builder Design Pattern
Using i10 Builder for building i10
Car i10 is ready
Engine Power:1000
Body Size:100
Wheel Size:10
Using i20 Builder for building i20
Car i20 is ready
Engine Power:2000
Body Size:200
Wheel Size:20

Builder Design pattern Description