我想扩展std :: string，但不是因为你可能会想 [英] I want to extend std::string, but not for the reason you might think

问题描述

我有一个方法，有效地接受一个字符串。然而，有一个非常有限的字符串子集我想使用。我在想象typedef'ing std :: string作为一些类，并调用显式的函数。我不知道这将工作，但是。想法？

I have a method that effectively takes a string. However, there is a very limited subset of strings I want to use. I was thinking of typedef'ing std::string as some class, and call the functions explicit. I'm not sure that would work, however. Ideas?

推荐答案

通常的规则仍然适用：该类不是设计为继承自，其析构函数不是虚拟的，所以如果你向上转换为std :: string基类，并让对象被销毁，你的派生类的析构函数不会被调用。

The usual rule still applies: the class isn't designed to be inherited from, and its destructor isn't virtual, so if you ever upcast to the std::string base class, and let the object be destroyed, your derived class' destructor won't be called.

如果你可以

否则，你可以使 std :: string 成为一个成员的类，而不是一个基类。或者你可以使用私有继承。这种方法的问题是你必须重新实现该类的字符串接口，使其可以用作字符串。

Otherwise, you could make the std::string a member of your class, rather than a base class. or you could use private inheritance. The problem with this approach is that you'd have to re-implement the string interface for the class to be usable as a string.

或者你可以定义你的类暴露一个返回内部 std :: string 对象的 getString（）函数。然后你仍然可以传递你自己的类，如果你尝试传递一个 std :: string ，编译器会抱怨，但内部字符串可以访问，当你需要它。这可能是最好的妥协。

Or you could just define your class to expose a getString() function which returns the internal std::string object. Then you can still pass your own class around, and the compiler will complain if you try to pass a std::string, but the internal string is accessible when you need it. That might be the best compromise.

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