paste.cpp

来自「Think in C++文中代码实现」· C++ 代码 · 共 80 行

// File from page 676 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).
//////////////////////////////////////////////////

//: PASTE.CPP -- Fixing a mess with MI
#include <fstream.h>
#include "..\15\vendor.h"

ofstream out("paste.out");

class mybase { // Repair vendor interface
public:
  virtual void v() const = 0;
  virtual void f() const = 0;
  // New interface function:
  virtual void g() const = 0; 
  virtual ~mybase() { out << "~mybase()\n"; }
};

class paste1 : public mybase, public vendor1 {
public:
  void v() const {
    out << "paste1::v()\n";
    vendor1::v();
  }
  void f() const {
    out << "paste1::f()\n";
    vendor1::f();
  }
  void g() const {
    out << "paste1::g()\n";
  }
  ~paste1() { out << "~paste1()\n"; }
};

main() {
  paste1& p1p = *new paste1;
  mybase& mp = p1p; // Upcast
  out << "calling f()\n";
  mp.f();  // Right behavior
  out << "calling g()\n";
  mp.g(); // New behavior
  out << "calling A(p1p)\n";
  A(p1p); // Same old behavior
  out << "calling B(p1p)\n";
  B(p1p);  // Same old behavior
  out << "delete mp\n";
  // Deleting a reference to a heap object:
  delete &mp; // Right behavior
}