Hi Dick,
because set(list) creates an unsorted collection without duplicate entrys
of the items in the list.
If you pass an empty list, the resulting set will also be an empty
collection.
A list containing an empty list evaluates non false, since it's not empty.
Maybe it helps you to compare them with the len-command.
len(set([])) returns 0, len([[]]) returns 1.
Marcel
At 11:44 AM 7/13/2008, Steve Willoughby wrote:
Dick Moores wrote:
Yes! A rule, not logic. I'm not contradicting Kent, just helping myself
understand. First the rule, then logic in the application of the rule.
And I
assume the rule is there in Python because it makes things work better.
Yes, so a statement like "if foo:" becomes an idiom for "if the
collection foo
has stuff in it:" which is handy whether foo is a text string or a list
of
objects.
Yes, I've been using that, a bit uneasily.
One question about the data I listed. Why is bool(set([])) false,
whereas bool([[]])
is true?
Dick
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