定義一個介面（Creator）用以建立物件，由子類（ConcreteCreator）決定建立物件的型別（Product或ConcreteProduct...）

struct Product {};

struct ConcreteProduct : Product {};

struct Creator
{
	virtual Product* FactoryMethod() { return new Product; }
	void AnOperation() { product = FactoryMethod(); }
private:
	Product * product;
};

struct ConcreteCreator : Creator
{
	Product* FactoryMethod() override { return new ConcreteProduct; }
};

int main()
{
	Creator* p = new ConcreteCreator;
	p->AnOperation();//ConcreteCreator::FactoryMethod() get called
}