std::auto_ptr or boost::shared_ptr for pImpl idiom?

Question

When using the pImpl idiom is it preferable to use a boost:shared_ptr instead of a std::auto_ptr? I\'m sure I once read that the boost version is

Answer 1

I tend to use auto_ptr. Be sure to make your class noncopyable (declare private copy ctor & operator=, or else inherit boost::noncopyable). If you use auto_ptr, one wrinkle is that you need to define a non-inline destructor, even if the body is empty. (This is because if you let the compiler generate the default destructor, impl will be an incomplete type when the call to delete impl_ is generated, invoking undefined behaviour).

There's little to choose between auto_ptr & the boost pointers. I tend not to use boost on stylistic grounds if a standard library alternative will do.