变量承接函数类型的方法

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重点：

1.当两个类没有共同基类。

采用函数模板：类具有相同的函数

class FirstCmd 
{
public:FirstCmd()=default;~FirstCmd() = default;void TestCmd() { std::cout << 10 << std::endl;};
};class SecondCmd
{
public:SecondCmd() = default;~SecondCmd() = default;void TestCmd() { std::cout << 20 << std::endl; };
};template<class T>
void Get(T* a)
{a->TestCmd();
}int main()
{int a = 3;int b = a * a * a-a;FirstCmd* first=new FirstCmd();SecondCmd* second =new SecondCmd();auto iter = dynamic_cast<FirstCmd*>(first);auto se = dynamic_cast<SecondCmd*>(second);if (iter == nullptr){Get(se);}else{Get(iter);}return 0;
}

2.当两个类有共同基类。

采用向下转型方式

class BaseCmd
{
public:BaseCmd() = default;~BaseCmd() = default;virtual void TestCmd() = 0;
};class FirstCmd:public BaseCmd
{
public:FirstCmd()=default;~FirstCmd() = default;virtual void TestCmd() { std::cout << 10 << std::endl;};
};class SecondCmd :public BaseCmd
{
public:SecondCmd() = default;~SecondCmd() = default;virtual void TestCmd() { std::cout << 20 << std::endl; };
};std::shared_ptr<BaseCmd> GetBaseCmd(bool check)
{if (check){return std::make_shared<FirstCmd>();}else{return std::make_shared<SecondCmd>();}
}int main()
{bool check{ false };auto base =GetBaseCmd(check);base->TestCmd();std::shared_ptr<BaseCmd> baseCmd = std::dynamic_pointer_cast<FirstCmd>(base);if (!baseCmd){baseCmd=  std::dynamic_pointer_cast<SecondCmd>(base);}if (baseCmd){baseCmd->TestCmd();}return 0;
}