Aleksey Gurtovoy <agurtovoy@meta-comm.com> writes:
The problem here is that the result of 'boost::bind( &add_two, _1 )' takes its argument by reference, while transform_iterator's 'dereference' implementation is:
typename super_t::reference dereference() const { return m_f(*this->base()); } ^^^^^^^^^^^^^
In our case, '*this->base()' produces a temporary 'int' which cannot be directly passed to 'm_f'.
Effectively, the issue prevents you from layering any iterator adaptors built with 'boost::bind' on top of 'transform_iterator',
Only if the underlying iterator is an input iterator whose dereference returns by value, right?
which, needless to say, is BAD.
Regrettable, I agree.
My sugesstion would be to replace the above with
typename super_t::reference dereference() const { typename iterator_reference<Iterator>::type x( *this->base() ); return m_f( x ); }
If it passes all tests I have no objections. -- Dave Abrahams Boost Consulting www.boost-consulting.com