selfmem.cpp

Think in C++ 第二版源码

//: C10:Selfmem.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Static member of same type
// ensures only one object of this type exists.
// Also referred to as a "singleton" pattern.
#include <iostream>
using namespace std;

class Egg {
  static Egg e;
  int i;
  Egg(int ii) : i(ii) {}
public:
  static Egg* instance() { return &e; }
  int val() { return i; }
};

Egg Egg::e(47);

int main() {
//!  Egg x(1); // Error -- can't create an Egg
  // You can access the single instance:
  cout << Egg::instance()->val() << endl;
} ///:~