Re: [boost] [bimap][multi_index][range] sub_range vs std::pair<iter, iter>

From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2007-05-24 09:46:30

Matias Capeletto skrev:
> On 5/23/07, "JOAQUIN LOPEZ MU?Z" <joaquin_at_[hidden]> wrote:
>> ----- Mensaje original -----

[snip]

>> Moreover, one can always convert the std::pair to a range
>> very easily, although this conversion would be much
>> simpler if iterator_range and sub_range provided ctors
>> taking std::pairs of iterators --Thorsten, would you
>> consider adding this a good idea?
> 
> They are already provided. I have just being playing with them with Boost.Bimap.

It's there implicitly because the two classes has a templated 
constructor that takes a Range template argument.

>>> 2) In any case do you think that including typedef for the returned
>>> range type will make code more readable?
>>> The idea is to define:
>>>
>>> typedef -range_type- sub_range; // the name can be different
>>> typedef -const_range_type- const_sub_range;
>>>
>>> So the user code will look like this:
>>>
>>> typedef bimap<string,int> bm_type;
>>> bm_type bm;
>>> //...
>>> bm_type::left_sub_range r = bm.left.range(...,...);
>> I am not sure. On one hand, the syntax above is obviously
>> more concise, but on the other hand a casual reader would
>> have to look up what sub_range is to fully understand the
>> code, whereas the std::pair is self explanatory and moreover
>> it's honored by the tradition of equal_range().
> 
> At least for Boost.Bimap, compare:
> 
> std::pair<
>     bm_type::map_by<name>::const_iterator,
>     bm_type::map_by<name>::const_iterator
> 
>> r = bm.by<name>().range(...,....);
> 
> with:
> 
> bm_type::map_by<name>::const_sub_range r = bm.by<name>().range(...,....);
> 
> Maybe "sub_range" is not the better word. IMO it is not a bad election.

boost::sub_range< bm_type::map_by<name> >
    r = bm.by<name>().range(...,...);

is not that bad IMO. This should work with or without dependency on 
Boost.Range. Without dependency there might be an extra conversion, I 
haven't timed code to see if it really matters.

-Thorsten