On Thu, 2008-04-17 at 00:22 +0300, Peter Dimov wrote:
Daniel Frey: ...
template< typename U > shared_ptr<U> shared_from_this( U* u );
This would even allow you to drop the template parameter of esft_light. Interesting.
That would only be possible if I drop shared_from_this(), which would break the interface for every use case. OTOH, if you consider a breaking change to the interface, it's easier for the user as he simply passes the this-pointer in all cases (except where he wants to pass a different pointer) and doesn't need to make a decision. The possibility of passing something else than "this"
Getting back to your proposed changes, I unfortunately can't think of a mutually satisfactory way to integrate them. I don't like
shared_ptr( shared_count & pn, Y* px );
because it moves from the lvalue pn, auto_ptr style. The proper interface wouldn't do that; it would copy from lvalues and move from rvalues by default, while still providing an explicit way to move from lvalues.
In fact my copy of the trunk already contains const shared_count& and a shared_count&& overload, since I also felt that taking and modifying a reference is too "dirty". I think I wouldn't mind the additional overhead in case of C++03, as I think that some other cases are optimized anyway, so it might not be that bad. If you like, I could post a patch and an analysis of all cases where it optimizes or pessimizes something. Adding yet another overload for the auto_ptr-style might not be worth it. Regards, Daniel