拆分C ++类声明 [英] Split a C++ class declaration

问题描述

我想知道我是否可以拆分C ++类声明

I want to know if I can split a C++ class declaration

原始班级

    class P
    {
        private: 
           int id;
           //some really secret method
           int secretMethod();
       protected:
           int x;
       public:
           P();
           int getX();
    };

我只想在.h中显示公共的和受保护的方法和属性，并在其他地方声明私有的，而类的用户看不到它.

I want to show in the .h only the public and protected method and attributes, and declare somewhere else the private, where the user of the class can't see it.

想要的类声明:

    class P
    {
       protected:
           int x;
       public:
           P();
           int getX();
    };

我想要这样做:

1. 我可以更改类的实现，并且该类的用户是透明的
2. 对于用户来说，查看更少的信息要比查看更多的信息更容易
3. 如果我更改类的实现，请更改我不想为类用户更改.h的私有属性和方法

推荐答案

是的，有可能但不是直接的方式.这是您的工作:

Yes, it is possible but not in the direct kind of way. Here is what you do:

my_object.h:

my_object.h:

struct my_object {
  void fun();

  my_object();
  my_object(my_object const&);
  ~my_object();

  my_object& operator = (my_object);

protected:
  void pfun();

private:
  struct impl;
  std::unique_ptr<impl> pimpl;
};

my_object.cpp:

my_object.cpp:

struct my_object::impl {
  void fun() { do stuff...}

  void pfun() { do other stuff... }

  int private_member;
};

my_object::my_object() : pimpl(new impl) {}
my_object::my_object(my_object const& o) : pimpl(new impl(*o.pimpl) {}
my_object::~my_object() {}

my_object& my_object::operator = (my_object o) { swap(pimpl, o.pimpl); return *this; }

void my_object::fun() { pimpl->fun(); }
void my_object::pfun() { pimpl->pfun(); }

如您所见，这需要大量工作，并且需要堆.平衡的一切……在需要时使用.

As you can see, it's a lot of work and requires the heap. Everything in balance...use when you need to.

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