From: Timmo Stange (ts_at_[hidden])
Date: 2007-02-16 16:05:44
Timmo Stange wrote:
> Such a combiner would violate the single pass traversal limitation
> of the input iterator concept. The cache solution allows dereferencing
> the same iterator multiple times to acquire the same value without
> calling the slot again, which already is a stronger guarantee than
> an input iterator usually provides. The combiner example in the
> docs makes use of it.
On a side note, I think this may have some funny implications. The
iterator_facade cannot return an iterator for the post-increment
operator, because dereferencing it would violate the same rule. So
I guess if you traverse the slot range in the combiner with "i++",
you will call all the slots without ever dereferencing the iterator,
while traversal with "++i" will not call them. Or am I missing
something here?
Regards
Timmo Stange