岫玉
C.132: Don't make a function virtual without reason
C.132:不要没有理由就将函数声明为虚函数
Reason(原因)
Redundant virtual increases run-time and object-code size. A virtual function can be overridden and is thus open to mistakes in a derived class. A virtual function ensures code replication in a templated hierarchy.
多余的虚函数会增加运行时和目标码的大小。虚函数可以被覆盖，也可以说对派生类对错误开放。在模板继承时，虚函数一定会引起代码重复。
Example, bad(反面示例)
<code>template<classt>classVector{public://...virtualintsize()const{returnsz;}//bad:whatgoodcouldaderivedclassdo?private:T*elem;//theelementsintsz;//numberofelements};/<classt>/<code>This kind of "vector" isn't meant to be used as a base class at all.
这种类型的"vector"根本就不会作为基类使用。
Enforcement(实施建议)
- Flag a class with virtual functions but no derived classes.
- 标记出没有派生类却但是却有虚函数的类。
- Flag a class where all member functions are virtual and have implementations.
- 标记出所有的函数都是虚函数却又包含实现的类。
原文链接
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c132-dont-make-a-function-virtual-without-reason
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