Re: [boost] [Fit]Â formal review starts today

Subject: Re: [boost] [Fit] formal review starts today
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2016-03-05 17:43:25

Le 05/03/2016 17:11, Paul Fultz II a écrit :
>
>
> On Saturday, March 5, 2016 at 6:40:49 AM UTC-6, Vicente J. Botet 
> Escriba wrote:
>
>     Le 05/03/2016 13:22, Peter Dimov a écrit :
>     > Rob Stewart wrote:
>     >> On March 4, 2016 3:27:08 PM EST, Paul Fultz II
>     <pfu..._at_[hidden] <javascript:>>
>     >> wrote:
>     >> >
>     >> > The library could switch to using `Callable`, if everyone feels
>     >> that is > better. However, I honestly prefer to make mutable
>     >> explicit. I would > like to hear feedback from other reviewers
>     as well.
>     >
>     > I do not object to your requiring ConstCallable. I made
>     > boost/std::bind const-neutral because this felt the right thing
>     to do
>     > - it's not bind's job to tell you what your function object
>     ought to
>     > do, it just reflects whatever it does. At the same time, stateful
>     > function objects do have limited applicability outside of for_each
>     > which specifically guarantees order and returns the function
>     object.
>     > You could pass bind( ++_1, 0 ) to generate_n and that's pretty
>     much it.
>     >
>     > So I do not see the requirement as a defect warranting
>     rejection. If
>     > users demand Callable support, you'll add it. If not, not.
>     >
>     >> If your library only requires Callable, then users can supply a
>     >> Callable or a ConstCallable. When you require a ConstCallable,
>     they
>     >> cannot supply a Callable. There may be valid reasons for that
>     >> restriction in certain cases, but they should be documented rather
>     >> than just imposed as a convention.
>     >
>     > That's true in principle. In practice though function objects
>     that are
>     > not ConstCallable are in 90% of the cases the result of a forgotten
>     > 'const' on operator() and not a deliberate decision. So requiring
>     > ConstCallable catches errors.
>     >
>     For me the question is if the functions provided by the library need
>     that the function object must be const or not.
>
> They do not need it. However, there can be some unexpected behavior 
> when the
> user uses mutable function objects, because the functions can be copied or
> moved multiple times.
Copied or moved? Does the library accepts move only function objects?
Do you have an example of unexpected behavior?

Vicente