Re: [boost] Re: Re: rtl (Range Template Library)

From: John Torjo (john.lists_at_[hidden])
Date: 2003-11-20 12:37:39

Matthew Wilson wrote:

>>Now that I think about it, a range concept does not even need to be so
> 
> complicated.
> 
>>As explained above (in the original message):
>>- a range is a pair of iterators
>>- it has typedefs for value_type,pointer,reference
>>   (no const_pointer,no const_reference)
>>- it's got begin() and end()
>>- it's got an operator bool() that returns true if the
>>   range is non-empty.
> 
> 
> I'm still of the opinion that all a range needs is ++(), bool() and *().
> Having said that, begin() and end() are starting to look attractive, from a
> practical pov. Hopefully others can shed light on where in the continuum
> between our ideas they lie. (Perhaps they'll lie outside it! :)
> 

Matt, that is not true.
Again, I've used it in real code, where I would find an element, and had to go 
to the previous one.

// real-life code
crange< const snapshots_array> found = rng::lower_bound( m_snapshots, 
mk_dummy_snapshot( m_current), snapshot_by_time);
if ( found.begin() != m_snapshots.begin() )
     // go to the first element whose time is earlier than current
     --found;

It all depends on the situation at hand. It the iterator can do it, so the range 
should.

Best,
John