On 16/6/2013 4:55 πμ, Tim Roberts wrote:
Nick the Gr33k <supp...@superhost.gr> wrote:
Because Python lets you use arbitrary values in a Boolean context, the net
result is exactly the same.
What is an arbitrary value? don even knwo what arbitrary means literally
in English.
In a long series separated by "or", the expression is true as soon as one
of the subexpressions is true. So, as a short-circuit, Python simply
returns the first one that has a "true" value. So, for example, these all
return 'abcd':
'abcd' or 'defg' or 'hjkl' ==> 'abcd'
0 or 'abcd' or 'defg' or 'hjkl' ==> 'abcd'
0 or None or 'abcd' or 'defg' or 'hjkl' ==> 'abcd'
Similarly, "and" returns the first "false" value, or if they're all true,
the last value. Why? Because it can't know whether the whole expression
is true unless it looks at every value. So:
0 and 1 and 'what' ==> 0
1 and 0 and 'what' ==> 0
1 and None and 0 ==> None
1 and 1 and 'what' ==> 'what'
Thank you Tim.
I decided that it's better to thing it through as:
The argument being returned in an "and" or "or" expression is the one
that *determined' the evaluation of the expression.
And actually what's being returned is not the argument itself but the
argument's value.
--
What is now proved was at first only imagined!
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