C + + Contemplative learning note Sixth chapters handle (reference counting pointer embryonic?) )

A simple point-coordinate class

Class Point {
Public
Point (): Xval (0), Yval (0) {}
Point (int x,int y): Xval (x), Yval (y) {}
int x () const {return xval;}
int y () const {return yval;}
point& x (int xv) {xval = XV; return *this;}
point& y (int yv) {yval = YV; return *this;}
Private
int Xval, yval;
};

Bind the handle to it on a layer of encapsulation

Controlling those operations through handle exposes those operations that are private to prevent users from manipulating the address of a point

It is more important to provide a reference count of point to bind multiple handle to Ppint to release the right to use the point

Operation to release point

Then add two classes

A reference count class Upoint

Class Upoint {
Friend class Handle;
Point P;
int u;

Upoint (): U (1) {}
Upoint (int x, int y):p (x, Y), U (1) {}
Upoint (const point& p0):p (P0), U (1) {}
};

One is that the handle handle class contains the pointer construction and destruction of Upoint when the count is +1

Release the pointer memory when counting to 0

Class Handle {
Public
Handle ();
Handle (int, int);
Handle (const point&);
Handle (const handle&);
handle& operator= (const handle&);
~handle ();
int x () const;
handle& x (int);
int y () const;
handle& y (int);
Private
upoint* up;
};

The full code is as follows:

1 //sample0.cpp: Defines the entry point of the console application. 2 //3 4#include"stdafx.h"5#include <iostream>6 7 classPoint {8  Public:9Point (): Xval (0), Yval (0){}TenPoint (intXinty): Xval (x), Yval (y) {} One     intX ()Const{returnxval;} A     intY ()Const{returnYval;} -point& x (intXV) {xval = XV;return* This; } -point& y (intYV) {yval = YV;return* This; } the Private: -     intxval, Yval; - }; -  + classUpoint { -FriendclassHandle; + Point p; A     intu; at  -Upoint (): U (1) {} -Upoint (intXintY):p (x, Y), U (1) {} -Upoint (Constpoint& p0):p (P0), U (1){} - }; -  in classHandle { -  Public: to Handle (); +Handle (int,int); -Handle (Constpoint&); theHandle (Consthandle&); *handle&operator=(Consthandle&); $~Handle ();Panax Notoginseng     intX ()Const; -handle& x (int); the     intY ()Const; +handle& y (int); A Private: theupoint*Up ; + }; -  $Handle::handle (): Up (Newupoint) {} $Handle::handle (intXintY): Up (Newupoint (x, y)) {} -Handle::handle (Constpoint& p): Up (NewUpoint (P)) {} -  thehandle::~Handle () { -     if(Up->u = =0)Wuyi delete up; the } -  WuHandle::handle (Consthandle& h): Up (h.up) {++up->u;} -handle& Handle::operator=(Consthandle&h) { About++h.up->u; $     if(--up->u = =0) { - delete up; -     } -     return* This; A } +  the intHandle::x ()Const{returnUp->p.x ();} - intHandle::y ()Const{returnUp->p.y ();} $  thehandle& handle::x (intx0) the { theUp->p.x (x0); the     return* This; - } in  thehandle& Handle::y (inty0) { theUp->p.y (y0); About     return* This; the } the  the  + intMain () - { the Handle H;BayiStd::cout << h.x () <<" "<< h.y () <<Std::endl; the     return 0; the}

View Code

C + + Contemplative learning note Sixth chapters handle (reference counting pointer embryonic?) )