----- Original Message ----- From: "Peter Dimov" <[EMAIL PROTECTED]> To: "Boost mailing list" <[EMAIL PROTECTED]> Sent: Wednesday, December 11, 2002 10:21 AM Subject: Re: [boost] Formal review: Optional library
> From: "Fernando Cacciola" <[EMAIL PROTECTED]> > > I still don't like to think of optional<> as a container, so I still don't > > like this reset. > > I don't see why. reset() has nothing to do with containership; it's a > generic shorthand for reconstructing an object in place. > > void X::reset(args) > > Effects: destroys the contents of *this (if any) > Postconditions: *this is equivalent to X(args) > OK. > > > Currently, you can change the value of the optional directly without any > > performance > > penalty like this: *opt = new_val, so I don't see any real need for > reset(). > > Not correct, *opt has undefined behavior when opt is uninitialized. > Funny... The truth is that *opt has defined behaviour even if it is uninitialized when used as an lvalue: it can be reset to initialized. IOWs, *opt=x is exactly like opt.reset(x). This is clearly documented, clearly shown on the examples, but apparently, clearly wrong :-) (otherwise, you and William wouldn't have mistaken it) I'll post a sub-thread to discuss this (mis?)feature on its own. It has important derivations, such as the need for the proxy and hence .value(). I think that if this behaviour is removed, the interface proposed by William might work fine. Fernando Cacciola _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
