[Python-Dev] [Python-checkins] cpython: Issue #14065: Added cyclic GC support to ET.Element

[Eli Bendersky]

On Fri, Mar 30, 2012 at 21:30, Benjamin Peterson <benjamin at python.org>wrote:

>  > +    def test_cyclic_gc(self):
> > +        class ShowGC:
> > +            def __init__(self, flaglist):
> > +                self.flaglist = flaglist
> > +            def __del__(self):
> > +                self.flaglist.append(1)
>
>
> I think a nicer way to check for cyclic collection is to take a
> weakref to an object, call the GC, then check to make sure the weakref
> is broken.
>
> > +
> > +        # Test the shortest cycle: lst->element->lst
> > +        fl = []
> > +        lst = [ShowGC(fl)]
> > +        lst.append(ET.Element('joe', attr=lst))
> > +        del lst
> > +        gc.collect()
>
> support.gc_collect() is preferable
>
> > +        self.assertEqual(fl, [1])
> > +
> > +        # A longer cycle: lst->e->e2->lst
> > +        fl = []
> > +        e = ET.Element('joe')
> > +        lst = [ShowGC(fl), e]
> > +        e2 = ET.SubElement(e, 'foo', attr=lst)
> > +        del lst, e, e2
> > +        gc.collect()
> > +        self.assertEqual(fl, [1])
>
>
Thanks for the insights, Benjamin. I'll explore these alternatives and will
submit a fix.

Eli
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