Hallo, The following code gives an error with g++ 4.1: #include <boost/bind.hpp> #include <boost/signal.hpp> struct connection { boost::signal<void()> disc_sig; }; struct statement { statement(connection & c); void disconnect() {} }; statement::statement(connection & c) { c.disc_sig.connect(boost::bind(&statement::disconnect, this)); } The error message is: D:/src/boost/boost/bind.hpp: In function 'void boost::visit_each(V&, const boost::_bi::value<T>&, int) [with V = boost::signals::detail::bound_objects_visitor, T = statement*]': D:/src/boost/boost/bind.hpp:239: instantiated from 'void boost::_bi::list1<A1>::accept(V&) const [with V = boost::signals::detail::bound_objects_visitor, A1 = boost::_bi::value<statement*>]' D:/src/boost/boost/bind/bind_template.hpp:150: instantiated from 'void boost::_bi::bind_t<R, F, L>::accept(V&) const [with V = boost::signals::detail::bound_objects_visitor, R = void, F = boost::_mfi::mf0<void, statement>, L = boost::_bi::list1<boost::_bi::value<statement*> >]' D:/src/boost/boost/bind.hpp:1213: instantiated from 'void boost::visit_each(V&, const boost::_bi::bind_t<R, F, L>&, int) [with V = boost::signals::detail::bound_objects_visitor, R = void, F = boost::_mfi::mf0<void, statement>, L = boost::_bi::list1<boost::_bi::value<statement*> >]' D:/src/boost/boost/visit_each.hpp:25: instantiated from 'void boost::visit_each(Visitor&, const T&) [with Visitor = boost::signals::detail::bound_objects_visitor, T = boost::_bi::bind_t<void, boost::_mfi::mf0<void, statement>, boost::_bi::list1<boost::_bi::value<statement*> > >]' D:/src/boost/boost/signals/slot.hpp:121: instantiated from 'boost::slot<SlotFunction>::slot(const F&) [with F = boost::_bi::bind_t<void, boost::_mfi::mf0<void, statement>, boost::_bi::list1<boost::_bi::value<statement*> > >, SlotFunction = boost::function<void ()(), std::allocator<void> >]' boost_signals.cpp:18: instantiated from here D:/src/boost/boost/bind.hpp:1208: error: no matching function for call to 'visit_each(boost::signals::detail::bound_objects_visitor&, statement* const&, int)' I tried this both on Fedora Core 5 and Windows/Cygwin. My command line is just: g++-4.1.0 -c boost_signals.cpp -ID:/src/boost Cheers, Nicola Musatti