finding the parent class (not superclass) of the currently executing method derived from a Borg class

seanacais kccnospam at glenevin.com
Mon Sep 8 22:10:20 CEST 2008


I want to create a class derived from a Borg class that can
instantiated as part of a script or be contained in other classes.
When methods from the Borg class are called, I would  like to know the
name of the class that contains the Borg class.

I've played a bit with inspect and _getframe from the sys module but
get inconsistent results.  The main problem is if the Borg class is
instantiated outside a containing class, then I need to go up a
different number of stack frames.  But this information isn't
available till after I've run out of stack frames.

Hopefully the following code better describes what I'm looking to do.

import sys

class Borg:
    _shared_state = {}
    def __init__(self):
        self.__dict__=self._shared_state

class Assimilated(Borg):
    valueByCaller = {}

    def __init__(self, setupvalue):
        print "In Assimilated.__init__()"
        print "setupvalue is: " + str(setupvalue)

        # would like  key to  be name of class (or module) that
        # contins Assimilated
        callerID =  sys._getframe(1).f_code.co_name

        self.valueByCaller[callerID] =  setupvalue

        print self.valueByCaller

    def action(self, calledvalue):
        print "In Assimilated.action()"
        print "self.__classname__: " + self.__class__.__name__
        print "calledvalue is: " + str(calledvalue)

        print "self.valueByCaller"
        print self.valueByCaller

        # need to get proper key depending on which class (or module)
        # made the call
#        print "0: " + sys._getframe(0).f_code.co_name
#        print "1: " + sys._getframe(1).f_code.co_name
#        print "2: " + sys._getframe(2).f_code.co_name
#        print "3: " + sys._getframe(3).f_code.co_name
        callerID =  sys._getframe(2).f_code.co_name
        print "callerID"
        print callerID

        if(self.valueByCaller[callerID] <= calledvalue):
            print "doing the action"


class A:
    assim_object = Assimilated(2)

    def __init__(self):
        self.assim_object.action(2)
        self.assim_object.action(3)

class B:
    assim_object = Assimilated(3)

    def __init__(self):
        self.assim_object.action(3)
        self.assim_object.action(4)

class C:
    assim_object = Assimilated(4)

    def __init__(self):
        self.assim_object.action(4)
        self.assim_object.action(5)


a=A()
b=B()
c=C()

obj=Assimilated(3)
#obj.action(3)


When I run this, I get the following output:

In Assimilated.__init__()
setupvalue is: 2
{'A': 2}
In Assimilated.__init__()
setupvalue is: 3
{'A': 2, 'B': 3}
In Assimilated.__init__()
setupvalue is: 4
{'A': 2, 'C': 4, 'B': 3}
In Assimilated.action()
self.__classname__: Assimilated
calledvalue is: 2
self.valueByCaller
{'A': 2, 'C': 4, 'B': 3}
callerID
<module>
Traceback (most recent call last):
  File "\CallerID.py", line 67, in <module>
    a=A()
  File "\CallerID.py", line 49, in __init__
    self.assim_object.action(2)
  File "\CallerID.py", line 41, in action
    if(self.valueByCaller[callerID] <= calledvalue):
KeyError: '<module>'

What I found most peculiar when I started this was that the
valueByCaller dictionary was completely populated before the __init__
method of a was executed.  I'm pretty sure that this has to do with
the difference between when the object gets instanced and when it gets
initialized, but I need to do some more research and reading to be
able to explain it to myself.

Thanks for any help you can give me.

Kevin



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