bears.cpp

Think in C++文中代码实现

// Non-printed example in "Thinking in C++" by Bruce Eckel
//////////////////////////////////////////////////
// From the compressed package ECKELT02.ZIP 4/11/95
// (Original ECKELT01.ZIP dated 2/21/95)
// Copyright (c) Bruce Eckel, 1995 
// Source code file from the book "Thinking in C++", 
// Prentice Hall, 1995, ISBN: 0-13-917709-4
// All rights reserved EXCEPT as allowed by the following 
// statements: You may freely use this file for your own 
// work, including modifications and distribution in 
// executable form only. You may copy and distribute this 
// file, as long as it is only distributed in the complete 
// (compressed) package with the other files from this 
// book and you do not remove this copyright and notice. 
// You may not distribute modified versions of the source 
// code in this package. This package may be freely placed 
// on bulletin boards, internet nodes, shareware disks and 
// product vendor disks. You may not use this file in 
// printed media without the express permission of the 
// author. Bruce Eckel makes no 
// representation about the suitability of this software 
// for any purpose. It is provided "as is" without express 
// or implied warranty of any kind. The entire risk as to 
// the quality and performance of the software is with 
// you. Should the software prove defective, you assume 
// the cost of all necessary servicing, repair, or 
// correction. 
// If you think you've found an error, please 
// email all modified files with loudly commented changes 
// to: [e-mail] (please use the same 
// address for non-code errors found in the book).
//////////////////////////////////////////////////

//: BEARS.CPP -- Containers & polymorphism
#include <iostream.h>
#include "..\14\tstack.h"

class bear {
public:
  virtual void who() const = 0;
  virtual ~bear() = 0 {} // Must have a body
};

class mama : public bear {
public:
  void who() const {
    cout << "Big bad mama bear" << endl;
  }
  ~mama() { cout << "~mama" << endl; }
};

class daddy : public bear {
public:
  void who() const {
    cout << "Thoughtful, Reserved daddy bear"
         << endl;
  }
  ~daddy() { cout << "~daddy" << endl; }
};

class baby : public bear {
public:
  void who() const {
    cout << "Little tiny baby bear" << endl;
  }
  ~baby() { cout << "~baby" << endl; }
};

main() {
  tstack<bear> bears; // Default to ownership
  bears.push(new baby);
  bears.push(new daddy);
  bears.push(new mama);
  tstackIterator<bear> goldy(bears);
  // Polymorphism in action:
  while(goldy) {
    goldy->who();  // Smart pointer call
    goldy++;
  }
}