Re: [boost] [Fit] upcoming formal review for Boost.Fit

Subject: Re: [boost] [Fit] upcoming formal review for Boost.Fit
From: paul Fultz (pfultz2_at_[hidden])
Date: 2016-03-03 13:45:06

> On Thursday, March 3, 2016 12:36 PM, Sam Kellett <samkellett_at_[hidden]> wrote:
> > On 3 March 2016 at 17:39, paul Fultz <pfultz2_at_[hidden]> wrote:
>> 
>>  > On Wednesday, March 2, 2016 2:56 PM, Bjorn Reese <
>>  breese_at_[hidden]> wrote:
>>  > > On 02/27/2016 05:16 PM, Vicente J. Botet Escriba wrote:
>>  >
>>  >>  Documentation:http://pfultz2.github.io/Fit/doc/html/
>>  >
>>  > In More Examples / Projections there is this example:
>>  >
>>  >    std::sort(std::begin(people), std::end(people),
>>  >              by(&Person::year_of_birth, _ < _));
>>  >
>>  > That strikes me as a very terse syntax, where the reader could easily
>>  > miss the fact that two values are being compared. Have you considered
>> 
>>  > the use of placeholders like _1 and _2 instead?
>> 
>>  They are already supported. The anonymous placeholders are only there to
>>  describe an operator(they are not bind expressions). It could also be
>>  written
>>  like this as well:
>> 
>>  std::sort(std::begin(people), std::end(people),
>>  by(&Person::year_of_birth, std::less_than<>()));
>> 
>>  The clarity of two parameters being passed to `std::less_than` is just as
>>  clear as when using the anonymous placeholders. The advantage of writing
>> 
>>  `_ < _` is that it is generic, SFINAE and constexpr friendly.
>> 
> 
> so if i understand correctly, that means that this work:
> 
> 
> std::sort(std::begin(people), std::end(people), by(&Person::year_of_birth,
> _2 < _1);
> 

> as one way to reverse sort. right?

Yes.

Paul