Home Original page

Why property works only for objects?

Bruno Desthuilliers bdesth.quelquechose at free.quelquepart.fr
Fri Mar 10 21:56:03 EST 2006 
Michal Kwiatkowski a écrit :
> Alex Martelli napisał(a):
> 
>>Wrong!  Of _course_ it's an option -- why do you think it matters at all
>>whether you're the creator of this object?!
>  
(snip)
>>
>>def insert_property(obj, name, getter, setter):
>>    class sub(obj.__class__): pass
>>    setattr(sub, name, property(getter, setter))
>>    obj.__class__ = sub
>>
>>See?  Of COURSE you can subclass -- not hard at all, really.
> 
> 
> Let me understand it clearly. If I change __class__ of an object,
> existing attributes (so methods as well) 
> of an object are still
> accessible the same way and don't change its values. Only resolution of
> attributes/methods not found in object is changed, as it uses new
> version of __class__ to lookup names. Is this right?

Attributes, yes. Not methods. Methods are looked up in the class. But in 
the example above (brillant, as usual), Alex dynamically creates a 
subclass of obj.__class__, so inheritence takes care of methods lookup.


> mk
More information about the Python-list mailing list