More Exceptional C++

Chapter 30. Smart Pointer Members, Part 1: A Problem with auto_ptr

Difficulty: 5

Most C++ programmers know they have to take special care for classes with pointer members. But what about classes with auto_ptr members? And can we make life safer for ourselves and our users by devising a smart pointer class designed specifically for class membership?

1. Consider the following class:

   // Example 30-1
   //
   class X1
   {
     // ...
   private:
     Y* y_;
   };
   

   If an X1 object owns its pointed-at Y object, why can't the author of X1 use the compiler-generated destructor, copy constructor, and copy assignment?

2. What are the advantages and drawbacks of the following approach?

   // Example 30-2
   //
   class X2
   {
     // ...
   private:
     auto_ptr<Y> y_;
   };
   

Solution

Recap: Problems of Pointer Members ...