Why can't I xor strings?
adalke at mindspring.com
Sun Oct 10 11:52:00 CEST 2004
Paul Rubin wrote:
> I think != is appropriate in this situation.
> if bool(x) != bool(y): ...
while I prefer my already mentioned
if bool(x) + bool(y) == 1:
print "One and only one given"
That's because the pure logic ones, both != and
xor, confuse me while arithmetic doesn't.
It's also extensible to, say, "all three
parameters are either empty strings or non-empty
if 0 < bool(x) + bool(y) + bool(z) < 3:
print "that's not allowed"
BTW, I've used an idiom like this with some
def blah(filename = None, infile = None, url = None):
if (bool(filename is None) + bool(infile is None) +
bool(url is None)) != 2:
raise TypeError("Must specify one and only one of "
"'filename', 'infile', or 'url'")
if filename is not None:
infile = open(filename)
elif url is not None:
infile = urllib.urlopen(url)
Try that with an xor.
dalke at dalkescientific.com
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