Descriptors and decorators

bruno.desthuilliers at gmail.com bruno.desthuilliers at gmail.com
Tue Oct 26 10:28:46 CEST 2010


On 25 oct, 17:18, Joost Molenaar <j.j.molen... at gmail.com> wrote:
> Thanks, Bruno.
> Your python-wiki page and walk-through for the Decorator code make it
> clear. I now finally understand that methods are in fact ordinary
> functions at the time the class is created, and that the descriptor
> protocol turns them into bound or unbound methods when they're
> accessed as attributes:
(snip)
> Cheers! Now I will try to wrap my brain around metaclasses and coroutines. ;-)

Metaclasses are nothing special, really. Python classes are plain
objects and you can as well instanciate a class directly - the "class"
statement being mostly syntactic sugar:

def func(obj, x):
    obj.x = x

NewClass = type("NewClass", (object,), {'__init__':func, 'foo':lambda
z: z.x + 2})

So in the end, a metaclass is just another plain class, that is used
to instanciate class objects.




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