Re: [boost] [iterator] Idea for "range_from_ref_iterator"

From: Shunsuke Sogame (mb2act_at_[hidden])
Date: 2006-04-09 20:41:06

David Abrahams wrote:
> Ion Gaztañaga <igaztanaga_at_[hidden]> writes:
> 
> 
>>>You haven't really explained what this thing is supposed to be doing.
>>>As far as I can tell from the code, it dereferences to the same
>>>location at each position.  If that's really what you intend, you
>>>ought to do something to ensure that its iterator category doesn't
>>>indicate it satisfies forward iterator requirements.
>>
>>A pair of "range_from_ref_iterator" simulates a pair of random access 
>>iterators that point to an array of N identical values.
> 
> 
> It's not a legal random access (or even forward) iterator if it
> visits the same *element* more than once in a traversal.  That's why I
> said the above about the iterator category.
> 
> 
>>>Seems like a reasonable idea, but I'm not sure whether it's useful
>>>enough to be included.  I'd definitely call it something other than
>>>range_from_ref_iterator, though.  constant_iterator or something like
>>>that seems appropriate.
>>
>>constant_iterator seems good, 
> 
> 
> Whoops, "constant iterator" is already overloaded with a different
> meaning.  Something else, maybe... "repeat iterator?"

I agree it is nice to have "verb" for 'range adaptors'.

     copy(x|repeated(10)|transformed..., outIter);

repeat_range(repeat_iterator pair) seems to make an object be a range:

     copy(x|repeated(1), outIter);

So generalized!
But as Mr.Abrahams pointed, it is pity repeat_iterator for now is
illegal. (I remember I wrote the same code as Mr.Gaztanaga's!)
Is it possible it can have a legal implementation? I don't know for sure...

-- 
Shunsuke Sogame