class API
{
public:
virtual test(std::string s)=0;
protected:
API(){};
};
class ImpleOne :public API {
public:
    void test(string s) override {
        std::cout << "現在是One在執行 " << s<<std::endl;
    }
};

int main(void)
{
API * pApi=new ImpleOne();
pApi->test();
return;
}

#include<iostream>
#include<string>
#include<map>
//建立函數指針 
typedef void* (*Constructor)();

//創建一個工廠.
class CObjectFactory
{
public:
    //注冊對應的類添加到容器中
    static void RegsiterClass(std::string classname, Constructor constructor)
    {
        constructors()[classname] = constructor;
    }
    //創建一個類的對象并返回
    static void* CreateObject(const std::string ClassName)
    {
        Constructor constructor = nullptr;
        if (constructors().find(ClassName) != constructors().end())
        {
            constructor = constructors().find(ClassName)->second;
        }
        if (constructor == nullptr)
        {
            return nullptr;
        }
        return (*constructor)();
    }
private:
    //返回一個容器
    static std::map<std::string, Constructor>& constructors()
    {
        static std::map<std::string, Constructor> instance;
        return instance;
    }

};

//注冊我們的類的宏定義
#define REG_CLASS(class_name) \
 class class_name##Helper{ \
 public:  \
    class_name##Helper(){ \
    CObjectFactory::RegsiterClass(#class_name,class_name##Helper::CreateObjFunc); \
    }; \
    static  void*CreateObjFunc() \
    { \
        return new class_name; \
    } \
 };\
 static class_name##Helper class_name##helper; //加入static是指只在頭文件中有效。

 //在這里可以通過讀取配置文件，或者直接修改REG_CLASS和CreateObject中的字符串，就可以完成對這個類的改變，或者更新 ，并不影響后面代碼的更改。
 REG_CLASS(ImpleOne)
 class AUTOFACTORY
 {
     public:
     std::shared_ptr<Api> CreateAPI()
     {
        
        std::shared_ptr<API> Apipointer(static_cast<API*>(CObjectFactory::CreateObject("ImpleOne")));
        return Apipointer;
     }
 }
 int main(void)
 {
    std::shared_ptr<Api> testpoint(AUTOFACTORY::CreateAPI());
    testpoint->test("我不是你爸爸!");
    return;
 }