[10658] in The GTK GIMP ToolKit mailing list archive
[gtk-list] Re: Signal and event management.
daemon@ATHENA.MIT.EDU (Havoc Pennington)
Thu Dec 3 17:53:15 1998
Date: Thu, 3 Dec 1998 13:08:11 -0600 (CST)
From: Havoc Pennington <rhpennin@midway.uchicago.edu>
Reply-To: Havoc Pennington <rhpennin@midway.uchicago.edu>
To: gtk-list@redhat.com
In-Reply-To: <199812031653.RAA22708@sandra.ctv.es>
Resent-From: gtk-list@redhat.com
On Thu, 3 Dec 1998, Enric J. wrote:
>
> What I need essentially is a way to extend the signal mechanism in Gtk
> without using signal_connect, or without the overhead of the signal_connect
> mechanism, I need a way to pass ALL GTK SIGNALS to my own objects, think
> for a while that If I have a form with let say 200 controls and I want to
> be able to process some of the signals in an OO way without knowing in
> advance what signals to call, I must to ask Gtk for a signal_connect for
> all 200 controls for all Gtk signals (a medium of 60 for object), that's
> about 12000 signal_connect calls, an overhead I want to elude.
>
See Tim's answer, or you can use the Gtk-- approach.
This is what Gtk-- does, maybe it will help to understand the source:
All widgets have an associated Class struct, that has a function for each
signal or virtualized operation (not all of them are signals). Gtk-- takes
the normal contents of this struct, and saves it somewhere else. Then it
installs its own custom functions which basically chain the signal out to
the C++ object via a method called signal_name_impl(), which by default
calls the original C function we saved, but can be overridden by user
subclasses.
This is all set up by a preprocessor which parses special "macros" like
SIGNAL_SPEC() in the .gen_h files, and creates the necessary _impl method,
replacement function to put in the Class (signal_name_callback), and
generates the struct where we will save the original C functions
(Gtk_c_signals_Name).
The way to figure it out is to look at say widget.gen_h and then
widget.h/widget.cc, to see what's generated.
Havoc
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