Question about classes and possible closure.

[Steven W. Orr]

This is all an intro learning experience for me, so please feel free to 
explain why what I'm trying to do is not a good idea.

In the Cookbook, they have a recipe for how to create global constants.

-----------------
class _const:
     class ConstError(TypeError): pass
     def __setattr__(self,name,value):
         if self.__dict__.has_key(name):
             raise self.ConstError, "Can't rebind const(%s)"%name
         self.__dict__[name]=value

import sys
sys.modules[__name__]=_const()
----------------

I'd like to be able to create constants within a class. (Yes I understand 
that uppercase names is a far better and easier convention but this is a 
learning experience for me.)

I can't get this to work, but my idea is that MyClass is defined thusly:

class ConstError(TypeError): pass
class Myclass:
     def mprint(self):
         print "C1 = ", self._C1

     # Define a subclass to create constants. It refs upself to access
     # the uplevel copy of self.
     class _const:
         class ConstError(TypeError): pass
         def __setattr__(_upself,name,value):
             if upself.__dict__.has_key(name):
                 raise self.ConstError, "Can't rebind const(%s)"%name
             else:
                 print "Just set something"
             upself.__dict__[name]=value

     # I want the const instance to be contained in this class so I
     # instantiate here in the constructor.
     def __init__(self):
         upself = self
         upself.consts = const()
         upself.consts._C1 = 0
         setattr(upself.consts, "_C1", 44)
         self = upself

Then the call in another file is this:
#! /usr/bin/python
from c2 import Myclass
foo = Myclass()
foo.mprint()
# end

Is it possible to nest a class in another class and is it possible to make 
this work?

TIA

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