Why can't I xor strings?

[dataangel]

I wrote a function to compare whether two strings are "similar" because
I'm using python to make a small text adventure engine and I want to it
to be responsive to slight mispellings, like "inevtory" and the like. To
save time the first thing my function does is check if I'm comparing an
empty vs. a non-empty string, because they are to be never considered
similar. Right now I have to write out the check like this:

if str1 and str2:
if not str1 or not str2:
return 0

Because python won't let me do str1 ^ str2. Why does this only work for
numbers? Just treat empty strings as 0 and nonempty as 1.

Regardless of whether this is the best implementation for detecting if
two strings are similar, I don't see why xor for strings shouldn't be
supported. Am I missing something? Inparticular, I think it'd be cool to
have "xor" as opposed to "^". The carrot would return the resulting
value, while "xor" would act like and/or do and return the one that was
true (if any).

[Andrew Dalke]

Alex

str1 != str2 and (str1+str2) == (str2+str1)

I guess I'd better stop here because I can't actually _prove_ the last
one of these actually implies one of the strings is empty but I can't
find counterexamples either...!-)

str1 = "a"
str2 = "aa"

Andrew
da***@dalkescientific.com