Frank Mori Hess:
On Friday 11 April 2008 12:11 pm, Peter Dimov wrote:
I'm still not 100% convinced that we need this functionality in shared_ptr. But if we do, it seems that the proper way to add it is to make shared_ptr issue an unqualified call to
sp_accept_owner( this, p );
It does provide an alternative to making shared_from_this() callable in constructors. As long as sp_accept_owner() is always run after enable_shared_from_this is set up (and there is no reason it can't be since shared_ptr is fully aware of enable_shared_from_this) then it is usable as a post constructor where shared_from_this can be used safely. Actually, you don't even need enable_shared_from_this if don't need to use shared_from_this() outside the postconstructor, since you are passed in the owning shared_ptr.
You're right! sp_accept_owner can indeed be used as a postconstructor. My original idea was for it to replace sp_enable_shared_from_this entirely, making enable_shared_from_this non-special and fully implementable in "user mode". This doesn't seem to be a problem for the use case you describe though. The programmer would just implement sp_accept_owner for the derived class and call sp_accept_owner( (esft*)this ) before using shared_from_this.