OK, this group finally let me replay to the list. I added the header file for apply and changed the line you mentioned to use apply<bool>(), but now it won't compile, comlaining about noncopyable objects. Any thoughts? ---snip--- old_test.cpp:87: instantiated from here /usr/include/boost/noncopyable.hpp:27: error: ` boost::noncopyable::noncopyable(const boost::noncopyable&)' is private /usr/include/boost/bind.hpp:186: error: within this context /usr/include/boost/bind.hpp: In member function `R boost::_bi::list1<A1>::operator()(boost::_bi::type<R>, F, A&) const [with R = bool, F = boost::apply<bool>, A = boost::_bi::list0, A1 = boost::_bi::bind_t<const boost::signal<bool ()(), boost::last_value<bool>, int, std::less<int>, boost::function<bool ()(), std::allocator<void> > >&, boost::_mfi::dm<boost::signal<bool ()(), boost::last_value<bool>, int, std::less<int>, boost::function<bool ()(), std::allocator<void> > >, widget>, boost::_bi::list1<boost::_bi::value<widget*> > >]': /usr/include/boost/bind.hpp:186: error: initializing argument 1 of `R boost::apply<R>::operator()(F) const [with F = boost::signal<bool ()(), boost::last_value<bool>, int, std::less<int>, boost::function<bool ()(), std::allocator<void> > >, R = bool]' --- In Boost-Users@yahoogroups.com, "Peter Dimov" <pdimov@m...> wrote:
Darren Vincent Hart wrote: [...]
struct widget { boost::signal<bool ()> sig; boost::signal<bool (char)> keypress; bool test() { cout << "widget::test() - sig empty: " << (sig.empty() ? "true" : "false") << endl; sig(); return true; } }; [...] // bind to a widget signal handler, BROKEN //handler<bool> handler_b( boost::bind<bool>(&widget::sig, &widget_a) ); // <-- Broken [...] // store the function object returned by binding a widget signal, BROKEN //boost::function<bool ()> fp = boost::bind(&widget::sig, &widget_a); // <-- BROKEN
// executre the functor returned by binding a widget signal, BROKEN // (builds, but doesn't really call widget_a.sig()) boost::bind(&widget::sig, &widget_a)(); // <-- Test if binding works at all, it doesn't
bind(&widget::sig, &widget_a)() gets you a reference to widget_a->sig since &widget::sig is a data member. You still need to call it.
bool call(signal<bool()> const & s) { return s(); }
bind(call, bind(&widget::sig, &widget_a)) ();
will probably do what you want.
You can use apply<> from <boost/bind/apply.hpp> instead of 'call':
bind(apply<bool>(), bind(&widget::sig, &widget_a)) (); // should call widget_a->sig
HTH