Re: [boost] Boost.RangeEx: contains?

Subject: Re: [boost] Boost.RangeEx: contains?
From: Giovanni Piero Deretta (gpderetta_at_[hidden])
Date: 2009-02-23 13:23:09

On Mon, Feb 23, 2009 at 6:54 PM, Mathias Gaunard
<mathias.gaunard_at_[hidden]> wrote:
> Eric Niebler wrote:
>
>> And that's my point exactly. I feel that this:
>>
>>  boost::find( rng | filtered(pred) )
>>
>> is more obscure than this:
>>
>>  boost::find_if( rng, pred );
>>
>> Not only that, but I presume their return types are different, too. The
>> first would return filtered iterators, the second the original iterators.
>> Isn't that right?
>
> Indeed.
>
> Which is why I suggested that boost::find return a [it, end[ range, rather
> than just the `it' iterator.
>
> That way you can do
>
> boost::empty(boost::find(rng | filtered(pred)));
>
> instead of
>
> auto rng2 = rng | filtered(pred);
> boost::find(rng2) != boost::end(rng2);
>

If I understand the documentation correctly, you can do
boost::find<boost::return_found_end>(rng | filtered(pred)) to get
exactly what you want. I find this very useful, but the syntax is a
bit verbose.

Also, a 'base' adaptor that removes a level of adaptation (i.e. the
base_type from a boost::iterator adaptor) would be very useful.

BTW, I hope to find the time to write a review myself.

-- 
gpd