huan's blog

Microsoft Specific

The __super keyword allows you to explicitly state that you are calling a base-class implementation for a function that you are overriding. All accessible base-class methods are considered during the overload resolution phase, and the function that provides the best match is the one that is called.

__super::member_function();

__super can only appear within the body of a member function.

With the introduction of attributes that inject code, your code might contain one or more base classes whose names you may not know but that contain methods that you wish to call.

Example

// deriv_super.cpp
struct B1 {
   void mf(int) {
      // ...
   }
};

struct B2 {
   void mf(short) {
      // ...
   }

   void mf(char) {
      // ...
   }
};

struct D : B1, B2 {
   void mf(short) {
      __super::mf(1);    // Calls B1::mf(int)
      __super::mf('s');  // Calls B2::mf(char)
   }
};

int main() {
}

END Microsoft Specific

中文意思：

__super是编译器关键词，是一个辅助工具，在多重继承和多级继承环境下很方便，当你需要调用基类成员时，不需要你记忆这个成员到底是哪个基类提供的，编译器会帮你找到正确的基类。如果存在二义性（比如有两个基类提供了相同名称的成员），编译器会报错，在错误信息中会指出有哪些基类具有此成员，此时你可以根据提示信息把__super修改成希望的基类。总之一句话——它帮你减少记忆负担。