wrapped.cpp

来自「Thinking in c++ 2nd edition,c++编程思想（第2版）」· C++ 代码 · 共 67 行

//: C01:Wrapped.cpp
// From "Thinking in C++, Volume 2", by Bruce Eckel & Chuck Allison.
// (c) 1995-2004 MindView, Inc. All Rights Reserved.
// See source code use permissions stated in the file 'License.txt',
// distributed with the code package available at www.MindView.net.
// Safe, atomic pointers.
#include <iostream>
#include <cstddef>
using namespace std;

// Simplified. Yours may have other arguments.
template<class T, int sz = 1> class PWrap {
  T* ptr;
public:
  class RangeError {}; // Exception class
  PWrap() {
    ptr = new T[sz];
    cout << "PWrap constructor" << endl;
  }
  ~PWrap() {
    delete[] ptr;
    cout << "PWrap destructor" << endl;
  }
  T& operator[](int i) throw(RangeError) {
    if(i >= 0 && i < sz) return ptr[i];
    throw RangeError();
  }
};

class Cat {
public:
  Cat() { cout << "Cat()" << endl; }
  ~Cat() { cout << "~Cat()" << endl; }
  void g() {}
};

class Dog {
public:
  void* operator new[](size_t) {
    cout << "Allocating a Dog" << endl;
    throw 47;
  }
  void operator delete[](void* p) {
    cout << "Deallocating a Dog" << endl;
    ::operator delete[](p);
  }
};

class UseResources {
  PWrap<Cat, 3> cats;
  PWrap<Dog> dog;
public:
  UseResources() { cout << "UseResources()" << endl; }
  ~UseResources() { cout << "~UseResources()" << endl; }
  void f() { cats[1].g(); }
};

int main() {
  try {
    UseResources ur;
  } catch(int) {
    cout << "inside handler" << endl;
  } catch(...) {
    cout << "inside catch(...)" << endl;
  }
} ///:~