On Mon, 31 Oct 2005 19:31:33 GMT, "Mark E. Fenner" <[EMAIL PROTECTED]> wrote:
>Hello all, > >I was migrating some code from sets.ImmutableSet to frozenset and noticed >the following: > >******code******** >#!/usr/bin/env python > >from sets import ImmutableSet > > >class MSet1(ImmutableSet): > def __init__(self, iterArg, myName="foo"): > ImmutableSet.__init__(self, iterArg) > self.name = myName > > >class MSet2(frozenset): > def __init__(self, iterArg, myName="foo"): > frozenset.__init__(self, iterArg) > self.name = myName > > >m1 = MSet1([1,2,3], myName = "donkey") >print m1 >print m1.name > >m2 = MSet2([1,2,3], myName = "kong") >print m2 >print m2.name >*********end code********** > >*********run********** >MSet1([1, 2, 3]) >donkey >Traceback (most recent call last): > File "./setTest.py", line 22, in ? > m2 = MSet2([1,2,3], myName = "kong") >TypeError: frozenset() does not take keyword arguments >*********end run******** > >I'm missing something and couldn't find it in the docs. Without researching it, I would guess that you have to override __new__ so as not to pass through the myName arg to the otherwise inherited and called-with-all-arguments __new__ of the base class. You could take care of the myName arg in the __new__ method too (by temporarily binding the instance returned by frozenset.__new__ and assigning the name attribute before returning the instance), or you can define __init__ to do that part. See many various posted examples of subclassing immutable types. Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
