标签：function redefine mf Effective virtual public pB class

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.

标签：function,redefine,mf,Effective,virtual,public,pB,class
来源： https://www.cnblogs.com/zoneofmine/p/15350001.html

本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享；
2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关；
3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关；
4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除；
5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。