[Python-Dev] Defining properties - a use case for class decorators?
Jim Jewett
jimjjewett at gmail.com
Wed Oct 19 15:44:09 CEST 2005
(In http://mail.python.org/pipermail/python-dev/2005-October/057409.html,)
Nick Coghlan suggested allowing attribute references as binding targets.
> x = property("Property x (must be less than 5)")
> def x.get(instance): ...
Josiah shivered and said it was hard to tell what was even intended, and
(in http://mail.python.org/pipermail/python-dev/2005-October/057437.html)
Nick agreed that it was worse than
> x.get = f given:
> def f(): ...
Could someone explain to me why it is worse?
I understand not wanting to modify object x outside of its definition.
I understand that there is some trickiness about instancemethods
and bound variables.
But these objections seem equally strong for both forms, as well
as for the current "equivalent" of
def f(): ...
x.get = f
The first form (def x.get) at least avoids repeating (or even creating)
the temporary function name.
The justification for decorators was to solve this very problem within
a module or class. How is this different? Is it just that attributes
shouldn't be functions, and this might encourage the practice?
-jJ
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