missing 'xor' Boolean operator

[Ethan Furman]

[fixed for bottom-posting]

Dr. Phillip M. Feldman wrote:
> MRAB-2 wrote:
> 
>>
>><snip>
>>
>>What values should 'xor' return? IMHO, if only one of the values is true
>>then it should return that value, otherwise it should return False.
>>
>>     1 xor 0 => 1
>>     0 xor 2 => 2
>>     1 xor 2 => False
>>     0 xor 0 => False
>>
>>This is because it's a Boolean operator, so it should fall back to
>>Boolean values when necessary, like 'not':
>>
>>     not 0 => True
>>     not 1 => False
>>
>>Also:
>>
>>     x and y and z => (x and y) and z
>>     x or y or z => (x or y) or z
>>
>>therefore:
>>
>>     x xor y xor z => (x xor y) xor z
>>
 > Suppose that 'xor' returns the value that is true when only one value is
 > true, and False otherwise.  This definition of xor doesn't have the 
standard
 > associative property, that is,
 >
 > (a xor b) xor c
 >
 > will not necessarily equal
 >
 > a xor (b xor c)
 >
 > To see that this is the case, let a= 1, b= 2, and c= 3.
 >
 > (a xor b) xor c
 >
 > yields 3, while
 >
 > a xor (b xor c)
 >
 > yields 1.  So, I'd prefer an xor operator that simply returns True or 
False.
 >
 > Phillip
 >

You are, of course, free to write your version however it makes sense to 
you and your team.  :)

Since the 'and' and 'or' already return objects (and objects evaluate to 
true or false), then 'xor' should behave likewise, IMO.  I expect that 
would be the case if it were ever added to the language.

~Ethan~