Arno Schödl wrote:

boost::reverse_iterator::dereference() is

typename super_t::reference dereference() const { return *boost::prior(this->base()); }

boost::constant_iterator<T>::reference_type is T const&.

So reverse_iterator< constant_iterator<T> >::dereference returns a reference to a temporary variable. Not good.

this->base() calls iterator_adaptor<>::base(), which returns a reference to the underlying iterator it holds. Passing that reference to boost::prior() means that prior() pre-decrements the iterator within the iterator_adaptor. It would be odd for that decrement operator to return anything but a reference to the decremented object, so boost::prior() returns a reference to its decremented argument, a reference to the decremented iterator within the iterator_adaptor. I see no problem. _____ Rob Stewart robert.stewart@sig.com Software Engineer, Core Software using std::disclaimer; Susquehanna International Group, LLP http://www.sig.com IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.