----- Original Message ----- From: "William E. Kempf" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, December 12, 2002 5:31 PM Subject: Re: [boost] Formal review: Optional library
> > Fernando Cacciola said: > > From: "Peter Dimov" <[EMAIL PROTECTED]> > >> From: "Fernando Cacciola" <[EMAIL PROTECTED]> > >> > From: "Peter Dimov" <[EMAIL PROTECTED]> > >> > optional<> is not intended to replace _all_ situations were optional > >> values > >> > are used. > >> > It is itended to be used on those situations were pointers are > >> difficult > >> to > >> > use; > >> > but I expect programmers to keep using pointers were appropriate. > >> For example, as I said before, optional arguments to a function > >> should > > not > >> > be coded > >> > with optional<> but with conventional pointers. > >> > >> Actually (just a minor observation) > >> > >> void f(optional<T> /*const &*/ opt); > >> > >> is different than > >> > >> void f(T const * pt); > >> > >> as the latter might potentially store 'pt' while the former cannot. > >> > > ? You mean that the code inside f() could hold onto 'pt'? > > Well, yes it can... but that would be nasty. > > It is supposed to know that ownership is not being handed in. > > The use of a pointer is reserved to convey optionality. > > It is? Then how do you ever transfer ownership ;). > Hmm... OK, I take that back. A function can use a pointer to optionally take ownership of an object. So optional<T> as an argument could communicate that this is not the case, which is what Peter meant (I think...) Fernando Cacciola _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
