Class properties without superclass properties

Question

I have an inheritance hierarchy whereby some of the classes have a class property named e.g., 'pickled'. I would like to get A.pickled if it exists or None if not — even if A derives from many classes including e.g., B and B.pickled exists (or not).

Right now my solution crawls A's __mro__. I would like a cleaner solution if possible.

@IfLoop I am using the class property to automatically pickle particular properties. I am also using another class property to automatically generate a user interface, and yet more class properties to automatically generate histories of parameter values. Do you have a better solution? — Neil G, Jun 10 '14 at 21:11

score 2 · Accepted Answer · edited May 23 '17 at 12:11

To bypass the normal search through the __mro__, look directly at the attribute dictionary of the class instead. You can use the vars() function for that:

return vars(cls).get('pickled', None)

You could just access the __dict__ attribute directly too:

return cls.__dict__.get('pickled', None)

but using built-in functions is preferred over direct access to the double-underscored attribute dictionary.

object.__getattribute__ is the wrong method to use for looking at class attributes; see What is the difference between type.__getattribute__ and object.__getattribute__?

type.__getattribute__ is what is used for attribute access on classes, but that'd still search the MRO too.

Thank you very much. We're lucky to have you on Stackoverflow. — Neil G, Jun 10 '14 at 21:38

score 0 · Answer 2 · answered Jun 10 '14 at 21:05

0

I'm not sure, but perhaps

try:
    return object.__getattribute__(cls, 'pickled')
except AttributeError:
    return None

answered Jun 10 '14 at 21:05

Neil G

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Class properties without superclass properties

2 Answers2

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