any trick to allow anonymous code blocks in python?

John Roth newsgroups at
Sat Jun 26 02:43:03 CEST 2004

"Doug Holton" <insert at> wrote in message
news:v6GdnWji9PwSMUHdRVn-uw at
> Is there any metaclass trick or something similar to allow anonymous
> code blocks?
> I'd like to be able to let users do something like this fictitious
> b = Button()
> b.OnClick =:
>      print "you clicked me"

No. If you're looking for GUI callbacks, there's a significant
gap between lambdas and bound methods. You could
use something like (not tested):

b.OnClick = (lambda : sys.stdout("You clicked me"))

which will work (assuming I've got the syntax right).

If you're doing anything other than a toy program, though,
the best approach is to wrap the GUI widget in a class,
and use a bound method of that class for the callbacks.

The example in the Tkinter chapter of the Python Library
Reference ( in the Python 2.3.3 docs) shows
how to do it. It's amazingly simple, it's completely object
oriented, and it gives you full access to the instance within
the callback.

John Roth

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