On Mon, Jan 30, 2017 at 4:03 PM, Irv Kalb <i...@furrypants.com> wrote: > It seems very odd that Python allows you to override the values of True and > False. In the code, True and False were clearly recognized as keywords as > they were colored purple. But there was no error message. > > You cannot assign new values to other keywords. Simple tests of things like: > > for = 5 > > while = 2 > > not = 3 > > As expected, all result in SyntaxError: invalid syntax. Why would Python > allow you to override the values of True and False? I wonder if this is some > sort of historical thing as these are the only keywords besides None that are > uppercased. This line: > > None = 5 > > Even gives a special SyntaxError: cannot assign to None
There are slightly different things going on here. Trying to assign to a piece of syntax like "while" makes absolutely no sense, but trying to assign to "None" is structurally sane, yet disallowed. IIRC there's only one non-assignable name in Python 2 (None), but as mentioned, Python 3 adds True and False to that. (Interestingly, Ellipsis is not included in that.) > I teach intro to programming using Python. May I please request that you consider teaching Python 3? Python 2 isn't going anywhere (for better or for worse), and Py3 is a superior language in many ways, not least of which is that it keeps text and bytes separate, giving text the full power that it should have. For a beginning programmer, this is very helpful; there's nothing to un-learn when going international. (There will be new nuances to be learned, such as RTL text, but nothing to unlearn.) Python 3 also fixes a number of other problems that Python 2 inherited from C, making it altogether a better language for teaching with. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
