Default signal handlers

[אנטולי קרס נר <tombackton gmail com>]

Hello,

I'm a gtkmm user and I'd like to write signals for some of my classes. I
noticed gtkmm widgets have default handlers, which are virtual protected
class methods. I want my classes to have them too for consistency, but I
couldn't figure out from the source code, how exactly they are
implemented.

When are the default handlers called? Do they emit the signal, or
they're called every time the signal is emitted? Are they called even if
there's an existing connection to the signal?

I want my signals to behave like normal gtkmm/sigc++ signals to make
sure they have the expected consistent behavior.

- Anatoly Krasner