[Python-3000] GUI events

[Greg Ewing]

Antoine Pitrou wrote:

> button = gui.Button(...)
> button.on_clicked += my_on_clicked_button

> Has anyone had any experience with this idiom? Are there any drawbacks?
> It looks more elegant than inheritance and overriding methods to me.

PyGUI currently has a form of this, except that you
only get to plug in one handler at a time. This is
enough to avoid the need for subclassing in many
cases, though.

I could support multiple handlers, but it would
make things substantially more complicated, and I'm
not convinced it's worth it. I rarely find the need
to install multiple independent handlers for an
event. Often I want to *override* a handler and
gain complete control, and then I find that
multiple-handler systems (e.g. gtk signals) tend
to hinder more than they help.

> (when I have to inherit a library-supplied class, I'm always worried
> that I could override existing methods/attributes by mistake

PyGUI uses names starting with underscores for all
its internal attribute names. I could use an even
stricter convention for internal names if people
thought it would be of benefit. Many of PyGUI's
classes are designed to be used by inheritance
(e.g. Window, View).

--
Greg