[Tutor] Another assert() question

[Marcel Wunderlich]

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