From: Frank Hess (frank.hess_at_[hidden])
Date: 2007-01-26 10:52:15
Hi,
I'd like to suggest a sentence be added to the boost.signals documentation
describing how to connect one signal directly to another signal. It took
me a while to realize I could do things like
signal.connect(boost::bind(boost::ref(otherSignal), _2));
wrapping a signal object in a boost::ref() call before passing it to
boost::bind(), to get around signals being noncopyable. Before this
epiphany, I kept writing trivial wrapper functions to use as slots when I
wanted to connect two signals :) I imagine others who are new to
boost.signals and boost in general would resort to similar tactics.
By the way, I hacked up a partial implementation of boost.signals which is
intended to be thread-safe, since I missed boost.signals so much in my
multi-threaded code. Would anyone would be interested in this? It's just
a few header files, and depends on boost (although not on boost.signals).
I just did the bare minimum I need for my own use: a signal template class,
signalslib::connection, and signalslib::scoped_connection. I didn't
implement return values because I don't use them. I didn't implement
boost::trackable because I don't see how to make automatic connection
management thread-safe when a signal is connected to an object's member
function. You really want to insure the slot is disconnected from the
signal before the object providing the slot is destroyed. Inheriting the
object from boost::trackable wouldn't seem to be good enough, since the
boost::trackable destructor wouldn't get called until after the object's
destructor. So you pretty much have to manually disconnect the connection
at the beginning of the object's destructor.
-- Frank