Subject: Re: [boost] [Fit]Â formal review starts today
From: Paul Fultz II (pfultz2_at_[hidden])
Date: 2016-03-05 11:11:04
On Saturday, March 5, 2016 at 6:40:49 AM UTC-6, Vicente J. Botet Escriba
> Le 05/03/2016 13:22, Peter Dimov a Ã©crit :
> > Rob Stewart wrote:
> >> On March 4, 2016 3:27:08 PM EST, Paul Fultz II <pfu..._at_[hidden]
> >> 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.
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