Re: [boost] [iterator] Is there any interest in Null Iterator Adaptor ?

Subject: Re: [boost] [iterator] Is there any interest in Null Iterator Adaptor ?
From: Oswin Krause (Oswin.Krause_at_[hidden])
Date: 2016-09-25 14:01:50

On 2016-09-25 19:19, Edward Diener wrote:
> On 9/25/2016 9:20 AM, Rahman Salim Zengin wrote:
>> Hi! It would be pleasure for me to hear about your precious thoughts.
>> 
>> https://github.com/rszengin/null_iterator
>> 
>> Best regards.
> 
> What do you mean by "when it is used" ?
> 
> The normal use of iterators is to traverse a sequence and return a
> value when dereferenced. I have a hard time fitting your nulliter
> adaptor into that functionality. Perhaps your docuemnetation needs to
> be more expansive about its functionality.

I agree an example is needed. I can not think of any example where i 
would like to fool one of the std:: algorithms.

Moreover, note that this iterator will never fulfil the requirements of 
a random access iterator even if it allows random access. Simply because 
std::iterator_traits<It>::reference must be T& and thus *it must not 
return a proxy object. Therefore it is not even a ForwardIterator.

Also more seriously i goubt you get distances right as for iterators a 
and b must hold: b == a + (b - a)

Best,
Oswin