Re: [boost] Re: [boost.range] comparison operators for iterator_range andsub_range

From: Pavol Droba (droba_at_[hidden])
Date: 2004-09-09 16:35:45

Hi,

On Thu, Sep 09, 2004 at 02:57:39PM -0600, Jonathan Turkanis wrote:
> 
> "Thorsten Ottosen" <nesotto_at_[hidden]> wrote in message
> news:chqcic$joc$1_at_sea.gmane.org...
> > Dear all,
> >
> > Another small issue have surfaced regarding operator==(), operator!=() and
> > operator<() (the latter currently not there).
> >
> > The current behavior is compare the two underlying iterators. I would suggest
> > to change this to compare the objects in the underlying range.
> > The motivation would be the follwoing:
> >
> > 1. comparing the iterators is seldom useful and can be done explicitlty or by
> > a new member function equal()
> > 2. comparing the objects is the range is highly useful and allows for code
> > like
> >
> > sub_range<string> sub = ...;
> > if( sub == "foo" )
> 
> Wouldn't it be natural to define a collection-oriented version of std::equal
> from <algorithm> to perform this test?

Such an algorithm is already in string_algo lib (maybe it will be move elsewhere
when better place will be found).

However, the point is somewhere else. There are operators for vector, list and etc.
It is natural to have it also for the iterator_range.

Plus it can simplyfy the usage as stated in the example above.

> 
> > 3. operator<() cannot be defined for iterators in general and hence we
> > couldn't put iterator_range into a set/map;
> 
> Would this be a lexicograpkical comparison?

This seem most natural.

Regards,

Pavol