[EMAIL PROTECTED] wrote:
> What I don't understand is
>>>import Tix
>>>
>>>def raise_exception():
>>> print 1/0
>>>
>>>if __name__ == '__main__':
>>> root = Tix.Tk()
>>> root.title("Exception demo")
>>>
>>> Tix.Button(root, text = "Don't press", command =
>
> raise_exception).pack()
>
>>> try:
>>> root.mainloop()
>>> except:
>>> print "An error has occured."
>>>--- snip ---
>>>
>>>The except part gets never executed.
>
> I thought the mainloop() function is something like
>
> def mainloop():
> e= get_event()
> if e:
> for w in widgets: w.handle(e)
>
> but apparently it is not.
The main loop is probably more like this:
def mainloop():
e= get_event()
if e:
try:
for w in widgets: w.handle(e)
except:
traceback.print_exc()
It's pretty common for GUI toolkits to trap exceptions in the event handler.
This can help make a more robust application - in my experience I don't really
want a bug in a handler to crash the whole app.
There is an undocumented hook that lets you change this - the function
Tk.report_callback_exception() is called to actually report the error. You can
redefine this function to do what you want. Here are a couple of examples:
http://zephyrfalcon.org/weblog/arch_d7_2003_01_04.html
http://groups.google.com/group/comp.lang.python/browse_thread/thread/ce0036f41da8a22f/c62177e5bb59b09c%23c62177e5bb59b09c?sa=X&oi=groupsr&start=1&num=3
Kent
--
http://www.kentsjohnson.com
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