什么是使用私有静态成员函数？ [英] What is the use of private static member functions?

问题描述

我在查看请求解析器

I was looking at the request parser from the boost::asio example and I was wondering why the private member functions like is_char() are static? :

class request_parser
{
  ...
  private:
    static bool is_char(int c);
  ...
};

它用于函数 consume 这不是一个静态函数：

It is used in the function consume which is not a static function:

boost::tribool request_parser::consume(request& req, char input)
{
  switch (state_)
  {
    case method_start:
    if (!is_char(input) || is_ctl(input) || is_tspecial(input))
    {
      return false;
    }
    ...

只有成员函数可以调用 is_char（），没有静态成员函数调用 is_char（）。所以有这些函数是静态的吗？

Only member functions can call is_char() and no static member function is calling is_char(). So is there a reason why these functions are static?

推荐答案

这个函数可以很容易地做独立，因为它不需要该类的对象在其中操作。使函数成为类的静态成员而不是自由函数具有两个优点：

This function could easily have been made freestanding, since it doesn't require an object of the class to operate within. Making a function a static member of a class rather than a free function gives two advantages:

1. 它赋予函数访问私有和受保护成员


2. 它以类似于命名空间的方式将该函数与类关联起来。

在这种情况下，只显示第二点。

In this case it appears only the second point applies.

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