What is NotImplemented ?
Alexandre Fayolle
alf at logilab.fr
Mon Apr 29 04:57:40 EDT 2002
Dans l'article <lkn0vq34fi.fsf at pc150.maths.bris.ac.uk>, Michael Hudson a écrit :
> Alexandre Fayolle <alf at logilab.fr> writes:
>
>> A quick question, here. What is the built in NotImplemented object?
>> And what can you do with it? I thought I could raise it as an
>> exception, but this is not the case (I use NotImplementedError instead).
>
> I think you can return it from implementations of, say, __add__ to
> mean roughly "I don't know what to do here".
<snip>
> Returning NotImplemented from the __add__ makes Python go off and call
> the __radd__ method.
Ahah! Thanks a lot.
The relevant documentation is in the Python Reference Manual, §3.2,
while I was looking for it in the library reference.
Alexandre Fayolle
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