Complicated filtered lists (python)

[aquavitae]

I need to create a list class for which each instance returns different items depending on who's requesting it. The structure is something like this:


class section:
def __init__(self):
self.items= []
#also iterator and access functions

class Master:
def __init__(self):
self.sections = [] # list of sections
def itersections...
def iteritems... # iterate over all items

master = Master()

class Subset:
def __init__(self):
self.master = master
self.filtersections = fromkeys(master.itersections, True)
self.filteritems = fromkeys(master.iteritems, True)

The first part is easy, I can create a list class which is linked to Master.sections and Subset.filtersections and calls filter() every time __getitem__ is called. The second part is to do something similar so that a section requested by Subset will only return the filtered items.

Any suggestions as to how I do this?