Factory Design Pattern
The factory design pattern is a type of creational pattern to create an object. In factory pattern, we create object without exposing the creation logic to the client and refer to newly created object using a common interface.
C++ Implementation
This example is a C++ implementation of the Shape example from tutorialpoints.
In this example, we are going to create a Shape interface and concrete classes implementing the Shape interface.
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#include <iostream>
#include <string>
using namespace std;
class Shape {
public:
virtual void draw() {}
};
class Rectangle : public Shape {
public:
void draw() {
cout << "Inside Rectangle draw() function." << endl;
}
};
class Square : public Shape {
public:
void draw() {
cout << "Inside Square draw() function." << endl;
}
};
class Circle : public Shape {
public:
void draw() {
cout << "Inside Circle draw() function." << endl;
}
};
class ShapeFactory {
public:
Shape* getShape(string shapeType) {
if (shapeType == "Circle") {
return new Circle();
} else if (shapeType == "Rectangle") {
return new Rectangle();
} else if (shapeType == "Square") {
return new Square();
} else {
return nullptr;
}
}
};
int main() {
ShapeFactory* sf = new ShapeFactory();
Shape* s1 = sf->getShape("Circle");
s1->draw();
Shape* s2 = sf->getShape("Rectangle");
s2->draw();
Shape* s3 = sf->getShape("Square");
s3->draw();
}