Re: [Boost-users] A forward iterator need not be default-constructible

Subject: Re: [Boost-users] A forward iterator need not be default-constructible
From: Dave Abrahams (dave_at_[hidden])
Date: 2011-10-03 12:51:04

on Mon Oct 03 2011, Krzysztof Żelechowski <giecrilj-AT-stegny.2a.pl> wrote:

> Dave Abrahams wrote:
>
>> 
>> on Sun Oct 02 2011, Andrew Sutton <asutton.list-AT-gmail.com> wrote:
>> 
>>> I would take that to mean that singularity is independent of type.
>> 
>> Although many types have singular values with respect to certain
>> operations (NULL is singular with respect to pointer dereference),
>> 
>> - Not every type has singular values
>> - Some types have multiple singular values
>> - In general, one type's singular values are distinct from another
>>   type's singular values
>> 
>> I don't know what you and Chris mean by "independent of type," but to me
>> this sounds like singularity is highly dependent on type.  
>
> It means iterators of the same type can be singular but need not, whereas 
> all (valid) iterators of the same type either must support random access 
> operations or must not, depending on the type in question.  

Not so, and I can think of a counterexample, but I'm getting tired of
arguing about it.  I don't think this is really relevant to the
discussion in the end, is it?

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com