Re: [Boost-users] [Range] Adaptors

Subject: Re: [Boost-users] [Range] Adaptors
From: Neil Groves (neil_at_[hidden])
Date: 2011-01-06 18:57:08

>
>
>> > If I had
>> >
>> > int f( int );
>> >
>> > boost::for_each( vec | boost::adaptors::reversed |
>> boost::adaptors::uniqued,
>> > f );
>> >
>> > and instead were able to write it as
>> >
>> > vec | boost::adaptors::reversed | boost::adaptors::uniqued | f;
>> >
>> > the final use of operator|() seems to pretty much imply eagerness in the
>> > same way that the for_each() does.
>>
>> Only if you happen to know that f is a function and will be treated
>> completely differently from the range adaptors.
>>
>>
>
Ignoring the implementation issues for a moment I would like to explain my
rationale for the current syntax. I consider the range adaptors to be
orthogonal to algorithms. I therefore perceive a syntactic difference
between the application of algorithms and adaptors to be an advantage. With
your example above I find the first version of the code more instantly
understandable since the most-significant operation (copy) is at the start
of the line. Therefore my personal opinion is that it is undesirable to
extend the pipe syntax to the application of algorithms.

Now considering implementation details I believe there are other reasons to
not extend the pipe syntax. When designing Boost.Range the extension of the
central idioms to user types and algorithms has been made simple. The range
adaptors are less simple to implement but are far less numerous than user
supplied algorithms. The current arrangement provides an extremely low
barrier for users wishing to implement range based algorithms.

I am very interested to hear the thoughts of yourself and the rest of the
boost community now that I have expanded upon some of the rationale. I am
open to being convinced.

>
> - Rob.
>
> Regards,
Neil Groves