Parent references: hot or not?

[Kiril Karaatanasov]

Hi this looks much as a case where aquisition is the answer to your questions.

See this example:

    import ExtensionClass, Acquisition

    class C(ExtensionClass.Base):
      color='red'

    class A(Acquisition.Implicit):

      def report(self):
        print self.color

    a=A()
    c=C()
    c.a=A()

    c.a.report() # prints 'red'

    d=C()
    d.color='green'
    d.a=a

    d.a.report() # prints 'green'

    a.report() # raises an attribute error

Aquisition is widely used in Zope. Here is alink to the standart guide:

http://debian.acm.ndsu.nodak.edu/doc/python-extclass/Acquisition.html

Hope this helps :)