Hello, given something like: class ProxyIterator : public boost::iterator_facade<ProxyIterator, Costly, boost::random_access_traversal_tag> { public: ProxyIterator(FactoryOfCostly* pF, int i ) : m_pFactory( pF ), m_index( i ) {} private: friend class boost::iterator_core_access; void decrement() {--m_index;} // ... and others Costly& dereference() const { m_value = m_pFactory->MakeCostlyAtIndex( m_index ); return m_value; } private: FactoryOfCostly* m_pFactory; int m_index; mutable Costly m_value; }; I cannot use this ProxyIterator with a boost::reverse_iterator adaptor because the implementation of reverse_iterator's dereference dereferences a temporary: // from reverse_iterator.hpp typename super_t::reference dereference() const { return *boost::prior(this->base()); } and in ProxyIterator, this dereference returns a reference to an internal member, m_value, that will immediately vanish out of existence. Bummer. What if reverse_iterator carried as member the decremented iterator instead of decrementing to a temporary on a dereference? In the current reverse_iterator implementation, decrement must behave properly on an end iterator, but not on a begin iterator. Can a begin iterator be decremented and still used for comparison purposes? -seb