Re: [boost] New Library Proposal: dual_state

From: Calum Grant (calum_at_[hidden])
Date: 2005-07-16 11:43:54

"David Abrahams" writes

> >> 
> >> Whoa; smart pointers and boost::optional are not very closely
> >> related beasts.  
> >
> > I mean, a weak_ptr and optional both have 0 or 1 pointees, 
> so there is 
> > at least a passing resemblance.
> 
> Merely a syntactic one.  optional is not a smart pointer; it just uses
> * and -> to provide access to its contained object.

But also semantically.  A smart pointer with a "copy on assignment"
policy would behave in almost exactly the same way. 

> > In the absence of Boost, I would probably use a 
> std::auto_ptr to store 
> > an optional field, which is, um, a smart pointer.  I realize that 
> > Optional is implemented slightly differently.
> 
> I wouldn't characterize it as a "slight" difference.

Okay, "completely".  Just an expression... :-) 

Calum