Darren Vincent Hart wrote:

Boost gurus,

I am using boost::bind in combination with boost::signals for a GUI toolkit. The signals return bool for convenience, but it is often desireable to bind a void function and connect it to a signal. Is there a convenient way to assign a return value for a void function.

As an example:

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struct panel { void print() { std::cout << "print" << std::endl; } }

struct widget { boost::signal on_event; }

panel p; widget w;

// is there some way to do something like this? w.on_event.connect(boost::bind_return(panel::print, &p, true));

You can do this with Lambda: using namespace boost::lambda; w.on_event.connect( (bind(panel::print, &p), true) ); but not with boost::bind, sorry. Not out of the box, anyway. template class override_return_t { private: F f_; V v_; public: typedef V result_type; override_return_t(F const & f, V const & v): f_(f), v_(v) { } result_type operator()() { f_(); return v_; } result_type operator()() const { f_(); return v_; } }; template override_return_t override_return(F const & f, V const & v) { return override_return_t(f, v); } #include #include #include <iostream> void g() { std::cout << "g()\n"; } int main() { boost::function f = override_return(boost::bind(g), true); std::cout << f() << std::endl; } You can even go a bit further and bring boost::bind one step closer to its lambda counterpart: template override_return_t, V> operator,(boost::_bi::bind_t const & f, V const & v) { return override_return_t, V>(f, v); } int main() { boost::function f = (boost::bind(g), true); std::cout << f() << std::endl; }