[Python-Dev] descriptor as instance attribute

Oleg Broytman phd at phdru.name
Mon Jan 9 16:51:35 CET 2012


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On Tue, Jan 10, 2012 at 01:32:13AM +1100, Jon Wells wrote:
> I can't find an answer to this grovelling through get user info. on
> descriptors.

   Read carefully http://users.rcn.com/python/download/Descriptor.htm

> Assuming desc() is a data descriptor class why are the following not the
> same???
>     class poop(object):
>         var = desc()
> and
>     class poop(object):
>         def __init__(self):
>             self.var = desc()
> In the second form the descriptor protocol for access to 'var' is
> ignored. 

   From http://users.rcn.com/python/download/Descriptor.htm:

...transforms b.x into type(b).__dict__['x'].__get__(b, type(b))..

   Please note the first type(b).

     Oleg Broytman            http://phdru.name/            phd at phdru.name
           Programmers don't die, they just GOSUB without RETURN.

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