I am not sure if you can do anything about changing the name of function to
make the clearer without breaking legacy code. I like lambda definition as
they state what is does. I prefer function objects when I want to pass in
behavior into a function rather then C-Style function object.


On Tue, Apr 14, 2020 at 8:38 PM Justin Bassett via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> Yes, I can do that. However, I can also do:
>
> std::transform(b1, e1, b2, e2, o, [](auto a, auto b) { return a + b;
> });
>
> Yet we do have std::plus. std::plus makes it more readable. Those lambda
> definitions work, but copy-pasting them everywhere is not productive. They
> get pulled out into their own header file of function objects, so I just
> write:
>
> std::transform(b, e, dest, plus(1));
>
> And now we're back where we started.
>
> Another benefit, albeit small, is that implementations could match on
> these function objects to provide more optimal implementations. For example:
>
> std::find_if(b, e, equal_to(2));
> // equivalent to:
> std::find(b, e, 2);
> // Possibly optimizable further into memchr
>
> Can I just use these little personal library function objects? Yes.
> However, perhaps it makes sense to have something like this in the standard
> function objects. If it doesn't, no problem, I'll keep using them myself.
>
> Thanks,
> Justin
>
> On Tue, Apr 14, 2020 at 6:11 PM Arthur O'Dwyer <arthur.j.odwyer_at_[hidden]>
> wrote:
>
>> On Tue, Apr 14, 2020 at 8:41 PM Justin Bassett via Std-Proposals <
>> std-proposals_at_[hidden]> wrote:
>>
>>> I use the function objects in <functional> all the time in conjunction
>>> with algorithms. However, sometimes, I find that I really want a curried
>>> function. For example:
>>>
>>> find_if(b, e, not_equal_to(0));
>>> transform(b, e, plus(1));
>>> copy_if(b, e, o, less(0))
>>>
>>
>> In C++14, you can say
>>
>> auto plus1 = [](auto x) { return x + 1; };
>> std::transform(b, e, dest, plus1);
>>
>> or even
>>
>> auto plus = [](auto x) { return [x](auto y) { return x + y; }; };
>> std::transform(b, e, dest, plus(1));
>>
>> if the parameter absolutely *must* be substituted in at run time.
>>
>> Do these not fit your needs for production code? If not, why not?
>>
>> –Arthur
>>
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