On Tuesday 18 March 2008 16:57, Peter Dimov wrote:
My current line of thinking is that we should refrain from introducing regressions. After
shared_ptr<X> px( new X, d );
px should contain the deleter d and - in the case when shared_from_this hasn't been called in the constructor - px.use_count() should be 1.
The use_count() is 1 with the patched version too, there's no regression there. _internal_shared_this is reset when px is constructed, so it doesn't inflate the use_count. By the way, I think I understand now what you were saying before about not seeing the need for 2 shared_ptrs in enable_shared_from_this. Since _internal_shared_this is only used from construction until ownership is transferred to a shared_ptr, and _user_deleter is only used after ownership is transferred, it can probably be optimized so that a single shared_ptr object fulfills both roles.
Is it really that important to make the shared_ptr instances created in X::X share ownership with px?
It is to me, as that is my primary motivation for making this patch. If they didn't share ownership I wouldn't bother with it, since the plain old "this" pointer would do just as well. -- Frank