RE: [boost] Re: [optional] new assignmet semantic and references

From: Brock Peabody (brock.peabody_at_[hidden])
Date: 2005-03-04 15:50:58

> On Behalf Of Fernando Cacciola
> Sent: Tuesday, March 01, 2005 10:39 AM
> To: boost_at_[hidden]
> Subject: [boost] Re: [optional] new assignmet semantic and references

> 
> So I think I will fix it unless users speak up...
> Though I will post this issue in the users list as well.

First I'd like to say that I love optional<>.  When I first read about it I
didn't think I'd use it much, but now I find myself using it all over the
place.  It's useful for so many things, but to me the most important is how
it improves my ability to make code self-documenting.
 
Personally, I like it the way it is.  I've used optional quite a bit and it
makes sense to me that operator= changes what an optional holds.  I don't
think it is a good idea to give operator= special semantics for references.

I think it odd, for instance, that given the following optionals:

    int a = 5, b = 6;

    boost::optional<int&> ra = a, rb = b;

this:

    ra = rb;

would have different behavior than:

    ra.reset();

    ra = rb;

I can understand the desire to mimic the semantics of built in C++
references in boost::optional, but one uses boost::optional precisely in
cases where one does not want those semantics - in cases where a reference
may not be present, and where you may want to change which object is
referred too.

My humble .02.

Brock