Re: difference between event and signal


2010/1/13 Ben Pfaff <blp cs stanford edu>:
> frederico schardong <frede sch gmail com> writes:
>> I'm confusing about the difference between event and signal.
> According to the GTK+ FAQ:
> First of all, Havoc Pennington gives a rather complete
> description of the differences between events and signals in his
> free book (two chapters can be found at
> Moreover, Havoc posted this to the gtk-list "Events are a stream
> of messages received from the X server. They drive the Gtk main
> loop; which more or less amounts to "wait for events, process
> them" (not exactly, it is really more general than that and can
> wait on many different input streams at once). Events are a
> Gdk/Xlib concept."
> "Signals are a feature of GtkObject and its subclasses. They have
> nothing to do with any input stream; really a signal is just a
> way to keep a list of callbacks around and invoke them ("emit"
> the signal). There are lots of details and extra features of
> course. Signals are emitted by object instances, and are entirely
> unrelated to the Gtk main loop. Conventionally, signals are
> emitted "when something changes" about the object emitting the
> signal."
> "Signals and events only come together because GtkWidget happens
> to emit signals when it gets events. This is purely a
> convenience, so you can connect callbacks to be invoked when a
> particular widget receives a particular event. There is nothing
> about this that makes signals and events inherently related
> concepts, any more than emitting a signal when you click a button
> makes button clicking and signals related concepts."
> --
> "Now I have to go wash my mind out with soap."
> --Derick Siddoway
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> gtk-list mailing list
> gtk-list gnome org

Frederico Schardong,
SOLIS - Open source solutions
Linux registered user #500582

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