holder2extr.hpp

C++_Templates这本书的随书源码

/* The following code example is taken from the book
 * "C++ Templates - The Complete Guide"
 * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
 *
 * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
template <typename T>
class Holder {
  // previously defined members
  //...

  public:
    Holder (Trule<T> const& t) {
        ptr = t.ptr;
        const_cast<Trule<T>&>(t).ptr = 0;
    }

    Holder<T>& operator= (Trule<T> const& t) {
        delete ptr;
        ptr = t.ptr;
        const_cast<Trule<T>&>(t).ptr = 0;
        return *this;
    }
};