是否需要在复制构造函数中复制静态成员，如果是，该怎么做？

Question

I have a class with a container that is declared static:

class test {

public: 
  test(const ClassA& aRef, const std::string& token); 
  test(const test& src); 
  ~test();

private: 
  ClassA& m_ObjRef;
  static std::vector<std::string> s_toks; 
};

The s_toks container is initialized as follows in the constructor defined in test.cpp:

std::vector<std::string> test::s_toks; 

    test::test(const ClassA& aRef, const std::string& token) 
       : m_ObjRef(aRef)
    {
       my_tokenize_function(token, s_toks);
    }

    test::test(const test& src)
       : m_ObjRef(src.m_ObjRef)
    {   
       /* What happens to s_toks; */
    }

If I do not copy s_toks, and s_toks is accessed from the new copied object, it is empty. What's the correct way to handle this?

Answer 1

A static data member is not bound to a single instance of your class. It exists for all instances, and to attempt to modify it in the class copy constructor makes little sense (unless you are using it to keep some kind of counter of instances). By the same token, it makes little sense to "initialize" it in any of the class constructors.

Answer 2

静态成员在类的所有实例之间共享，因此在构造函数中初始化它是没有意义的，也不会在复制构造函数中复制它。

Answer 3

Supporting other people's comments, this link provide a good explanation with examples: http://www.learncpp.com/cpp-tutorial/811-static-member-variables/

Unless you wish to access the static variable in all instances of the class, there is no need to declare it static.