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 07:40:34

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 <pfultz2_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.

Vicente