[Python-bugs-list] [ python-Bugs-501264 ] Metaproperties

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Bugs item #501264, was opened at 2002-01-09 04:09
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Category: Type/class unification
Group: Feature Request
>Status: Closed
>Resolution: Wont Fix
Priority: 5
Submitted By: Walter Dörwald (doerwalter)
>Assigned to: Guido van Rossum (gvanrossum)
Summary: Metaproperties

Initial Comment:
When defining properties in a metaclass the
setter function won't be called during the
class object construction:
---
class Meta(type):
   def getname(self):
      return self._name + "!"

   def setname(self, name):
      self._name = name

   name = property(getname, setname)

class Element(object):
   __metaclass__ = Meta

   name = "test"
---

print Element.name results in a "AttributeError: type 
object 'Element' has no attribute '_name'" but there 
is a 'name' attribute in Element.__dict__

http://www.python.org/2.2/descrintro.html clearly 
describes this behaviour, but is it possible to 
changes this to make metaproperties work (without 
having to fiddle with the dict in Meta.__new__)?

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>Comment By: Guido van Rossum (gvanrossum)
Date: 2002-01-09 06:03

Message:
Logged In: YES 
user_id=6380

I'm afraid this is how it's gonna be -- the metaclass
doesn't get control until after the body of the class
statement is executed. That's not easy to change. Closing
this as Won't Fix. Feel free to email me directly about
this.

----------------------------------------------------------------------

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