指向虚拟成员功能

Pointers to a virtual member functions

本文关键字：功能 虚拟成员      更新时间：2023-10-16

考虑以下代码

class BASE
{
  public:
            virtual void test_f(){std::cout<<"BASE::test_fn";}
};
class DERIVED:public BASE
{
    public:
            virtual void test_f(){std::cout<<"DERIVED::test_fn";}
};
void (BASE::*p_base)() = &BASE::test_f;

p_base是指向类成员函数的指针，但它是多态性的。这意味着

DERIVED a;
(a.*p_base)();

将打印派生:: test_f

我如何获取指向基类的test_f的指针以进行非多态性调用？

示例：

#include <iostream>
#include <functional>
class BASE
{
  public:
            virtual void test_f(){std::cout<<"BASE::test_fn";}
};
class DERIVED:public BASE
{
    public:
            virtual void test_f(){std::cout<<"DERIVED::test_fn";}
};
int main()
{
  // prints Derived
  void (BASE::*p_base)() = &BASE::test_f;
  DERIVED a;
  (a.*p_base)(); 
  auto f = std::mem_fun(&BASE::test_f);
  f(&a);
  
  // prints Base
  a.BASE::test_f();
  auto callLater = [&a]() { a.BASE::test_f();};
  callLater();  
}
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