Re: [boost] [smart_ptr] questions about some regression test cases

From: Daniel Frey (d.frey_at_[hidden])
Date: 2008-04-28 03:48:03

On Sun, 2008-04-27 at 20:27 -0400, Frank Mori Hess wrote:
> On Sunday 27 April 2008 15:02, Daniel Frey wrote:
> > My questions result from the observation that in the virtual dtor of
> > enable_shared_from_this, I tried BOOST_ASSERT( _shared_count.empty() ),
> 
> Are you aware that will abort the program in the case of a derived 
> constructor calling shared_from_this() then throwing?  It might be worth 
> considering making it a requirement that no constructor can throw after 
> calling shared_from_this though, see the first half of an earlier post:
> 
> http://lists.boost.org/Archives/boost/2008/04/135372.php
> 

Consider:

class Object {
  static map< string, shared_ptr< Object > > cache;

  Object()
  {
    cache.insert( make_pair( "foo", shared_from_this() ) );
    throw 42;
  }
};

With the above BOOST_ASSERT(_shared_count.empty()), ::abort() seems to
most sensible thing we can do, otherwise it would lead to very dangerous
situations where cache contains a shared_ptr to a deleted object.

Regards, Daniel