[boost] Re: safe_bool alternative?

From: Daniel Frey (daniel.frey_at_[hidden])
Date: 2003-11-27 13:02:30

Douglas Paul Gregor wrote:
> On Thu, 27 Nov 2003, Daniel Frey wrote:
> 
>>So the question is: Why should we add bool_testable at all? I think that
>>the operators library should offer it to make it easy for those that are
>>unaware (and probably ignorant) to the problem at all. Users add
>>operator bool(). The operators library allows them to add a single line
>>to protect it. They don't need to know the exact details. That's better
>>than doing nothing and it's easier to learn about Peter's idiom.
>>Hopefully they switch to Peter's idiom when they have time, but since
>>then, bool_testable should be helpful.
> 
> When we accept a library in Boost, we do so only when we can agree that we
> have the best interface with the proper semantics that anyone can think
> of. bool_testable does not (and, to the best of our knowledge, can not)
> give us the proper semantics. We won't use bool_testable and we won't
> recommend it to users; why would we include it? Is Peter's idiom _really_
> that hard to implement?

OK, you are right. We have bool_testable in CVS, so we are discussing 
whether or not it should be removed (and probably replaced by a good 
explanation of Peter's idiom) or if it should be officially released in 
1.31.0. I think it should be removed, I would just like to make sure 
that we agree on it. If I find some time at the weekend, I'll try to 
write some appropriate docs and prepare the patch to remove 
bool_testable. Even if we want bool_testable later, we can still add it 
in 1.32.0.

Regards, Daniel

-- 
Daniel Frey
aixigo AG - financial solutions & technology
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eMail: daniel.frey_at_[hidden], web: http://www.aixigo.de