Re: [boost] Report from Mont Tremblant C++ Committee meeting

From: Daryle Walker (darylew_at_[hidden])
Date: 2005-10-28 03:01:02

On 10/18/05 9:50 AM, "Fernando Cacciola" <fernando_cacciola_at_[hidden]>
wrote:

> Hamish Mackenzie wrote:
[SNIP]
>> Could the unifying concept OptionalPointee be implemented as free
>> functions?
> 
> Of course.
> 
> Notice that there are alternatives for safe_bool() that doesn't require
> dropping * and ->.
> These alternatives fix the problem with optional<bool>.
> One example is to simply provide operator !, used like this:
> 
> if ( !!opt )
> is_initialized();
> 
> (this is what my initial boost submission did)

I would find having type with an "operator not" but not any Boolean
conversion to be a surprise.  In fact, I filed a bug for Boost.Rational
having this problem.  (But I think that case was by accident, not design.)
The double-not operator as a workaround for Boolean conversion is an idiom
that we should NOT be introducing.

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT hotmail DOT com