id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4189	Add better support for non-default constructible function objects	Daniel Walker	jeffrey.hellrung	boost::transform_iterator is required to be default constructible, but not all function objects are. For example, boost::mem_fn_t is not default constructible. To allow transform_iterator to model DefaultConstructible with any function object type, Peter Dimov suggested using boost::optional. Thanks to Samuel Debionne for identifying and reporting the problem.	Feature Requests	new	Boost 1.43.0	iterator	Boost 1.42.0	Problem		transform_iterator