从基类特定函数调用子类方法 [英] call sub class method from base class specific function

问题描述

我有一个关于在C ++编程中处理虚函数的问题。我有这样的东西：

  template< class T> 
 class baseClass 
 {
 virtual void doSomething（T& t）{
 //一些baseClass特定代码
} 
 
 void doSomethingElse（ T& t）{
 //一些baseClass特定代码
 
 this-> doSomething（t）; 
} 
} 
 
模板< class T> 
 class subClass 
 {
 virtual void doSomething（T&）{
 //某些子类相关代码
} 
} 
  
 
 <$> 
 
 <$> 
 
 <$> p $ p $  int main（int argc，char * argv []）
 {
 subClass< anyType> * subClassObject = new subClass< anyType>（）; 
 subClassObject-> doSomethingElse（anyTypeObject）; 
} 
  

....并且调用 doSomethingElse 方法，这个方法将调用基类的 doSomething 方法，而不是子类。

我想要的是调用子类的 doSomething 方法（而不是 baseClass ）。

任何人都可以告诉我如何完成这项工作吗？ 可以通过 CRTP 完成：

  template< class T，class Derived> 
 class baseClass 
 {
 void doSomethingElse（T& t）{
 //一些baseClass特定代码
 static_cast< Derived *>（this） - > doSomething （T）; 
} 
} 
 
模板< class T> 
 class subClass：public baseClass< T，subClass> 
 {
 void doSomething（T&）{
 //一些与子类相关的代码
} 
} 
  

请参阅此讨论虚拟模板方法

I've got a question concerning handling of virtual function in C++ programming. I have something like this:

template<class T>
class baseClass
{
    virtual void doSomething(T& t) {
        // some baseClass specific code
    }

    void doSomethingElse(T& t) {
        // some baseClass specific code

        this->doSomething(t);
    }
}

template<class T>
class subClass
{
    virtual void doSomething(T&) {
        // some subclass related code
    }
}

Now, if I construct an object of type subClass....

int main(int argc, char *argv[])
{
    subClass<anyType> * subClassObject = new subClass<anyType>();
    subClassObject->doSomethingElse(anyTypeObject);
}

.... and call the doSomethingElse method of the base class, this method will call the doSomething method of the base class and not of the sub class.

What I want to have, is calling the doSomething method of the subclass (not of the baseClass).

Can anybody tell me how to accomplish that?

解决方案

You could accomplish it with CRTP:

template<class T, class Derived>
class baseClass
{    
    void doSomethingElse(T& t) {
        // some baseClass specific code
        static_cast<Derived*>(this)->doSomething(t);
    }
}

template<class T>
class subClass : public baseClass<T, subClass>
{
    void doSomething(T&) {
        // some subclass related code
    }
}

See this for discussion about virtual template methods

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