to invalidate a range

[Ellery Newcomer]

On 08/12/2011 06:34 PM, Jonathan M Davis wrote:
>>
>> Forgive my being dense, but where is this 'as long as' coming from? If
>> your range only points to ends in e.g. a linked list, how is it supposed
>> to retrieve elements in the middle? I'm having a hard time visualizing a
>> range over a node based container that doesn't point to a node in the
>> middle (at some point in time). The range points to the node to retrieve
>> the current front quickly, the node can get removed, the removed
>> function won't know its invalidating the range without playing yon
>> internal games, ergo stable remove cannot be.
>
> Are you familiar with iterators? This will be a lot easier if you are. An
> iterator points to one element and one element only. In C++, you tend to pass
> around pairs of iterators - one pointing to the first element in a range of
> elements and one pointing to one past the end. You then usually iterate by
> incrementing the first iterator until it equals the second.
>

Now you're just bludgeoning me into apathy (though my ability to 
communicate seems lacking). The iterator is an abstraction. Beneath it, 
in a node based container, [I expect] will be a pointer to a node, which 
might point to any node in the container. This means that removing any 
node could potentially invalidate a range somewhere. When such a 
conflict arises, you cannot both perform the removal and keep a valid 
range, regardless of whether you even knew of the conflict.