Subject: Re: [boost] [Fit]Â 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