Abstract Factory Pattern

Introduction: The abstract factory pattern is used for the construction of product families. The abstract factory refers to a factory pattern used when there are multiple abstract roles.The abstract factory pattern can provide an interface to the client, so that the client can create product objects in multiple product families without specifying the specific product.

Difference: Compared with the factory method pattern, the abstract factory pattern is that the factory method pattern is for one product series, while the abstract factory pattern is for multiple product series, that is, the factory method pattern is one product series and one factory class, while the abstract factory pattern is a factory class for multiple product families.In the abstract factory pattern, the client is no longer responsible for the creation of objects, but leaves this responsibility to the specific factory class, and the client is only responsible for calling objects, thus clarifying the responsibilities of each class.And when a series of interrelated products are designed into a factory class, the client's call will become very simple, and if you want to replace this series of products, you only need to replace a factory class.

Advantages:

1. The advantages of having the factory method pattern

2. It is easy to expand a product level, in line with the principle of opening and closing

Disadvantages:

1. It is very difficult to expand a product family. It does not conform to the open-closed principle. It is necessary to modify the interface class of the top-level factory, which does not conform to the open-closed principle.

Case:

#include using namespace std;class AbstractApple {public:virtual void show()=0;};class ChinaApple :public AbstractApple{public:virtual void show() {cout << "china apple" << endl;}};class UsaApple :public AbstractApple {public:virtual void show() {cout << "usa apple" << endl;}};class AbstracBanana {public:virtual void show() = 0;};class ChinaBanana :public AbstracBanana {public:virtual void show() {cout << "china banana" << endl;}};class UsaBanana :public AbstracBanana {public:virtual void show() {cout << "usa banana" << endl;}};class AbstractFactory {public:virtual AbstractApple* create_apple() = 0;virtual AbstracBanana* create_banana() = 0;};class ChinaFactory :public AbstractFactory {public:virtual AbstractApple* create_apple() {return new ChinaApple();}virtual AbstracBanana* create_banana() {return new ChinaBanana();}};class UsaFactory : public AbstractFactory {public:virtual AbstractApple* create_apple() {return new UsaApple();}virtual AbstracBanana* create_banana() {return new UsaBanana();}};int main(){AbstractFactory* af;af = new ChinaFactory;AbstracBanana* ab;ab = af->create_banana();ab->show();AbstractApple* aa;aa = af->create_apple();aa->show();return 0;}