Design Patterns 1: Abstract Factory

提供一个界面，用于创建一系列相关的对象。

struct AbstractProductA {};
struct ProductA1 : AbstractProductA {};
struct ProductA2 : AbstractProductA {};

struct AbstractProductB {};
struct ProductB1 : AbstractProductB {};
struct ProductB2 : AbstractProductB {};

struct AbstractFactory
{
	virtual AbstractProductA* CreateProductA() = 0;
	virtual AbstractProductB* CreateProductB() = 0;
};

struct ConcreteFactory1 : AbstractFactory
{
	AbstractProductA* CreateProductA() override { return new ProductA1; }
	AbstractProductB* CreateProductB() override { return new ProductB1; }
};

struct ConcreteFactory2 : AbstractFactory
{
	AbstractProductA* CreateProductA() override { return new ProductA2; }
	AbstractProductB* CreateProductB() override { return new ProductB2; }
};

int main()
{
	AbstractFactory* F1 = new ConcreteFactory1;
	AbstractFactory* F2 = new ConcreteFactory2;

	auto A1 = F1->CreateProductA();
	auto A2 = F2->CreateProductA();
	auto B1 = F1->CreateProductB();
	auto B2 = F2->CreateProductB();
}