我可以获得多态行为，而不使用虚拟函数？ [英] Can I get polymorphic behavior without using virtual functions?

问题描述

由于我的设备，我不能使用虚拟功能。假设我有：

  class Base 
 {
 void doSomething（）{} 
} ; 
 
 class Derived：public Base 
 {
 void doSomething（）{} 
}; 
 
 //在任何地方
 {
 Base * obj = new Derived; 
 obj-> doSomething（）; 
} 
  

obj-> doSomething code>将只调用 Base :: doSomething（）

调用 Derived ？的 doSomething / p>



我知道我可以在之前放置虚拟 c> Base 它解决了问题，但我受到我的设备的限制，编译器不支持它。

解决方案

您可以将基类指针转换为派生类并调用函数。

  Base * obj = new Derived; 
 Derived * d = static_cast< Derived *>（obj）; 
 d-> doSomething（）; 
  

由于doSomething（）没有被声明为virtual，所以应该得到派生实现。

Because of my device I can't use virtual functions. Suppose I have:

class Base
{
    void doSomething() { }
};

class Derived : public Base
{
    void doSomething() { }
};

// in any place
{
    Base *obj = new Derived;
    obj->doSomething();
}

the obj->doSomething() will call just the Base::doSomething()

Is there a way with Base *obj, to call the doSomething of the Derived?

I know I can just put a virtual before doSomething() of Base it solve the problem, but I'm limited by my device, the compiler doesn't support it.

解决方案

You could down cast the base class pointer to the derived class and call the function.

Base* obj = new Derived;
Derived* d = static_cast<Derived*>( obj ); 
d->doSomething();

Since doSomething() is not declared virtual, you should get the derived implementation.

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