Re: [Boost-users] Library Interface Design

From: Brian Allison (brian_at_[hidden])
Date: 2006-09-14 14:28:21

David Abrahams wrote:

>"Peter Dimov" <pdimov_at_[hidden]> writes:
>
>  
>
>>No, a singular iterator is not a valid object and it fulfills no
>>invariants. 
>>    
>>
>
>That's arguable.  From my POV, if it's in a state that a legal program
>can create, it's within the invariant by definition.
>
>  
>

Then (if I read you correctly) even undefined behavior is within the 
invariant? Or have I been misunderstanding that legal programs can cause 
UB? I've always considered that UB is to be treated as "not maintaining 
the invariant but it's not my fault".

But then, whether we consider UB within the invariant (and hence that an 
iterator is by definition always within the invariant) or whether we 
consider UB outisde of the invariant but one which doesn't break 
correctness (and hence that unassigned iterators are not capable of 
being within/outside of an invariant)....

  ... is there any practical difference between those two points of view?

thanks,
Brian