[Python-Dev] very slow compare of recursive objects (original) (raw)
Neal Norwitz neal@metaslash.com
Mon, 20 Jan 2003 10:50:17 -0500
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On Mon, Jan 20, 2003 at 10:32:50AM -0500, Tim Peters wrote:
[Tim] >Tuples can't be recursive,
[Guido] > Oh yes they can be: > > >>> L = [] > >>> t = (L, L) > >>> L.append(L) > >>> That's an example of a tuple containing a recursive structure; there's still no way, starting at t, to get back to t. I think mutation is required for that. Like L = [None] t = (L, L) L[0] = t Then t[0]0] is t and that's what I mean by "recursive tuple" (a tuple that can be reached from itself).
What about:
>>> t = ([],)
>>> t[0].append(t)
>>> print t
([([...],)],)
>>> print t[0][0] is t
True
Not sure if that's a tuple containing a recursive structure or a recursive tuple.
Neal
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