[Mailman-Users] Python's "false"
Barry A. Warsaw
bwarsaw at cnri.reston.va.us
Thu Dec 2 17:03:11 CET 1999
>>>>> "PH" == Pete Holsberg <pjh at mccc.edu> writes:
PH> What does Python use for the value of "false"?
- the singleton object None
- numeric zero of all types, i.e. integer 0, float 0.0
- an empty list, tuple, or dictionary, i.e. [], (), {}
- the empty string, i.e. '' or ""
You can also make instances act false by returning a false value from
a __nonzero__() method, e.g.
>>> class Foo:
... def __init__(self, x): self.x = x
... def __nonzero__(self): return self.x
...
>>> f = Foo(0)
>>> if f: print 'not false'
...
>>> f = Foo(1)
>>> if f: print 'not false'
...
not false
See also <http://www.python.org/doc/current/ref/lambda.html>
-Barry
More information about the Mailman-Users
mailing list