class A{
    /*提供一个接口*/
    public:
            static A *instance(){
                if(m_instance==null){
                        m_instance=new A();
                }
                return m_instance;
            }
    /*将类的构造方法声明为private，在类外实例化对象*/
    private:
            A();
            A(const A &);
            ~A();
            A & operator =(const A &);
    private:
            static A* m_instance;
};

class AbstractFruit{
public:
     virtual void ShowName()=0;
};
class Apple:public AbstractFruit{
public:
    virtual void ShowName(){        
        cout<<"Apple"<<endl;
    }
};
class Orange:public AbstractFruit{
public:
    virtual void ShowName(){        
        cout<<"Orange"<<endl;
    }
 };
 // 简单工厂模式
class FruitFactory{
public:
    static AbstractFruit* CreateFruit(string fruitName){
        if (fruitName == "Apple") {
            return new Apple();
        } else if (fruitName == "Orange") {
            return new Orange();
        }
        return nullptr;
    }
};
//
void test(){
    AbstractFruit* fruit = FruitFactory::CreateFruit("Apple");
    fruit->ShowName();
}