missing 'xor' Boolean operator

[Ethan Furman]

MRAB wrote:
> Ethan Furman wrote:
> 
>> Robert Kern wrote:
>>
>>> On 2009-07-14 14:56, Dr. Phillip M. Feldman wrote:
>>>
>>>> != does do what I want, except that it doesn't indicate to someone 
>>>> reading
>>>> the code that the operands are being treated as logicals.  
>>>> (Readability is
>>>> supposed to be one of the major selling points of Python).  But, 
>>>> this is
>>>> probably good enough.
>>>
>>>
>>>
>>> In the words of those greater than myself, "Not every one-liner needs 
>>> to be in the standard library."
>>>
>>> def xor(a, b):
>>>     return bool(a) != bool(b)
>>>
>>
>> Let's see...
>>
>>   and returns the last object that is "true"
>>   or  returns the first object that is "true"
>>
>> so should xor return the only object that is "true", else False/None?
>>
>> def xor(a, b)
>>     if a and b:
>>         return None
>>     elif a:
>>         return a
>>     elif b:
>>         return b
>>     else:
>>         return None
>>
> How about:
> 
> def xor(a, b):
>     return not b and a or not a and b

In [12]: not 1 and 0 or 1 and not 0
Out[12]: True

In [13]: not 0 and 0 or 0 and not 0
Out[13]: 0

In [14]: not 1 and 1 or 1 and not 1
Out[14]: False

In [15]: not [] and [] or [] and not []
Out[15]: []

Doesn't produce consistent objects, sometimes bool, sometimes something 
else.  'Course, it all depends on what you need.

~Ethan~