Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > So in Python 2.2, Python introduced two new built-in names, True and > False, with values 1 and 0 respectively: > > [steve@sylar ~]$ python2.2 > Python 2.2.3 (#1, Aug 12 2010, 01:08:27) > [GCC 4.1.2 20070925 (Red Hat 4.1.2-27)] on linux2 > Type "help", "copyright", "credits" or "license" for more information. >>>> True, False > (1, 0) >>>> type(True) ><type 'int'> >
Also in Python 2.2 (and I think earlier but I don't have anything earlier to check) there was an interesting property that while all other integers from -1 to 99 were optimised to share a single instance, there were actually 2 instances of 0 and 1: Python 2.2.3 (#1, Sep 26 2006, 18:12:26) [GCC 3.2.3 20030502 (Red Hat Linux 3.2.3-56)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> 2-1 is 1 1 >>> True is 1 0 >>> (True is 1) is 0 0 >>> (True is 1) is False 1 The code for the win32api made use of this fact to determine whether to pass int or bool types through to COM methods. -- Duncan Booth http://kupuguy.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
