missing 'xor' Boolean operator
steven at REMOVE.THIS.cybersource.com.au
Thu Jul 16 01:37:02 EDT 2009
On Wed, 15 Jul 2009 21:05:16 +0200, Jean-Michel Pichavant wrote:
> Didn't know that.
> So if I resume:
> - not 'foo' => False
> - 'foo' or 'foo' => 'foo'
> I may be missing something, but honestly, Guido must have smoked some
> heavy stuff to write such logic, has he ?
No, it's perfectly reasonable, and not at all the product of mind-
altering drugs. Other languages do the same thing.
for x in alist or blist or clist:
will select the first non-empty list and iterate over that.
Every object in Python has a truth value. By convention, we say that
objects are Something or Nothing.
0 None  '' are examples of Nothing, or false values.
1 2.5 [x, y, z] 'foo' are examples of Something, or true values.
Note the distinction between lower-case "false" and "true" (adjectives),
and title-case False and True (nouns).
`if x: ... else:` branches according to whether x is Something or
Nothing, not whether it is True or False.
The operators `and` and `or` also return Something or Nothing, short-
circuiting as appropriate.
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