Effective C++ 笔记 —— Item 36: Never redefine an inherited non-virtual function.

本文主要是介绍Effective C++ 笔记 —— Item 36: Never redefine an inherited non-virtual function.，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

Consider:

class B 
{
public:
    void mf();
    // ...
};

class D : public B { /*...*/ };

D x; // x is an object of type D

B *pB = &x; // get pointer to x
pB->mf();

D * pD = &x; // get pointer to x
pD->mf();

That's because in both cases you're invoking the member function mf on the object x. Because it's the same function and the same object in both cases, it behave the same way.

it won't if mf is nonvirtual and D has defined its own version of mf:

class D : public B 
{
public:
    void mf(); // hides B::mf; see Item 33
    // ...
};

pB->mf(); // calls B::mf
pD->mf(); // calls D::mf

The reason for this two-faced behavior is that non-virtual functions like B::mf and D::mf are statically bound (see Item 37). That means that because pB is declared to be of type pointer-to-B, non-virtual functions invoked through pB will always be those defined for class B, even if pB points to an object of a class derived from B, as it does in this example.

Things to Remember:

• Never redefine an inherited non-virtual function.

这篇关于Effective C++ 笔记 —— Item 36: Never redefine an inherited non-virtual function.的文章就介绍到这儿，希望我们推荐的文章对大家有所帮助，也希望大家多多支持为之网！