noisy.h

C++编程思想第二版第一册答案

//: C20:Noisy.h
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// A class to track various object activities
#ifndef NOISY_H
#define NOISY_H
#include <iostream>

class Noisy {
  static long create, assign, copycons, destroy;
  long id;
public:
  Noisy() : id(create++) { 
    std::cout << "d[" << id << "]"; 
  }
  Noisy(const Noisy& rv) : id(rv.id) {
    std::cout << "c[" << id << "]";
    copycons++;
  }
  Noisy& operator=(const Noisy& rv) {
    std::cout << "(" << id << ")=[" <<
      rv.id << "]";
    id = rv.id;
    assign++;
    return *this;
  }
  friend bool 
  operator<(const Noisy& lv, const Noisy& rv) {
    return lv.id < rv.id;
  }
  friend bool 
  operator==(const Noisy& lv, const Noisy& rv) {
    return lv.id == rv.id;
  }
  ~Noisy() {
    std::cout << "~[" << id << "]";
    destroy++;
  }
  friend std::ostream& 
  operator<<(std::ostream& os, const Noisy& n) {
    return os << n.id;
  }
  friend class NoisyReport;
};

struct NoisyGen {
  Noisy operator()() { return Noisy(); }
};

// A singleton. Will automatically report the
// statistics as the program terminates:
class NoisyReport {
  static NoisyReport nr;
  NoisyReport() {} // Private constructor
public:
  ~NoisyReport() {
    std::cout << "\n-------------------\n"
      << "Noisy creations: " << Noisy::create
      << "\nCopy-Constructions: " 
      << Noisy::copycons
      << "\nAssignments: " << Noisy::assign
      << "\nDestructions: " << Noisy::destroy
      << std::endl;
  }
};

// Because of these this file can only be used
// in simple test situations. Move them to a 
// .cpp file for more complex programs:
long Noisy::create = 0, Noisy::assign = 0,
  Noisy::copycons = 0, Noisy::destroy = 0;
NoisyReport NoisyReport::nr;
#endif // NOISY_H ///:~