missing 'xor' Boolean operator

[Anthony Tolle]

On Jul 15, 8:32 pm, Paul Rubin <http://phr...@NOSPAM.invalid> wrote:
> Among other things, that uses quadratic time!  Why do you want to keep
> popping items from that list instead of iterating through it anyway?
>
> Anyway, I think you wrote something close to this:
> ...

Very true!  I didn't think about the problems with pop().  I was using
it as a shortcut for pulling off the first operand.  I forgot that if
you start with an initial operand of "False", the result will be the
same (0 xor X = X)

While I'm not sure how useful it would be, here's a version of the
first function that returns one of the operands (ala AND and OR),
except in the case where there is an even number of True elements,
where it returns False:

def xor(*operands):
    r, rprime = False, False
    for x in operands:
        xprime = bool(x)
        if rprime:
            if xprime:
                r, rprime = False, False
        else:
            r, rprime = x, xprime
    return r

>>> xor(0, 0)
0
>>> xor(0, 1)
1
>>> xor(1, 0)
1
>>> xor(1, 1)
False
>>> xor(0, 1, 2)
False
>>> xor(0, 1, 2, 3)
3
>>> xor(None, [])
[]