On Sat, 18 May 2013 15:52:56 +0100
Richard Oudkerk <shibt...@gmail.com> wrote:
> On 18/05/2013 3:18pm, Antoine Pitrou wrote:
> > It works fine:
> >
> > $ ./python sbt.py
> > <__main__.Node object at 0x7f3acbf8f400> <__main__.Node object at
> > 0x7f3acbf8f878>
> > <__main__.Node object at 0x7f3acbf8f878> <__main__.Node object at
> > 0x7f3acbf8f400>
> >
> > The reason is that, when you execute "del self.next", this removes the
> > last reference to self.next and destroys it immediately.
>
> So even more contrived:
>
> class Node:
> def __init__(self, x):
> self.x = x
> self.next = None
> def __del__(self):
> print(self.x, self.next.x)
> del self.x
>
> a = Node(1)
> b = Node(2)
> a.next = b
> b.next = a
> del a, b
> gc.collect()
Indeed, there is an exception during destruction (which is ignored as
any exception raised from __del__):
$ ./python sbt.py
1 2
Exception ignored in: <bound method Node.__del__ of <__main__.Node object at
0x7f543cf0bb50>>
Traceback (most recent call last):
File "sbt.py", line 17, in __del__
print(self.x, self.next.x)
AttributeError: 'Node' object has no attribute 'x'
The only reason this currently succeeds is that the objects end up in
gc.garbage, of course.
Regards
Antoine.
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