[Python-Dev] Boolean type for Py3K?

[Barry A. Warsaw]

>>>>> "KY" == Ka-Ping Yee <ping@lfw.org> writes:

    KY> I wondered to myself today while reading through the Python
    KY> tutorial whether it would be a good idea to have a separate
    KY> boolean type in Py3K.  Would this help catch common mistakes?

Almost a year ago, I mused about a boolean type in c.l.py, and came up
with this prototype in Python.

-------------------- snip snip --------------------
class Boolean:
    def __init__(self, flag=0):
        self.__flag = not not flag

    def __str__(self):
        return self.__flag and 'true' or 'false'

    def __repr__(self):
        return self.__str__()

    def __nonzero__(self):
        return self.__flag == 1

    def __cmp__(self, other):
        if (self.__flag and other) or (not self.__flag and not other):
            return 0
        else:
            return 1

    def __rcmp__(self, other):
        return -self.__cmp__(other)

true = Boolean(1)
false = Boolean()
-------------------- snip snip --------------------

I think it makes sense to augment Python's current truth rules with a
built-in boolean type and True and False values.  But unless it's tied
in more deeply (e.g. comparisons return one of these instead of
integers -- and what are the implications of that?) then it's pretty
much just syntactic sugar <0.75 lick>.

-Barry