Mixed expiration stuff.py

#!/bin/env python

class ExpirationInterface():
  def setExpiration(self,value):
    setattr(self,self.expiration_property,value)

  def getExpiration(self):
    getattr(self,self.expiration_property)

class Principal( BaseClass, ExpirationInterface ):
  expiration_property = "prop1"
  prop1 = 5


def __main__():
  p = Principal()

  print p.prop1

  p.setExpiration(4);

  print p.prop1