[Python-Dev] Making None a keyword

M.-A. Lemburg mal@lemburg.com
Fri, 26 Apr 2002 09:58:36 +0200

Guido van Rossum wrote:
> I'd like to make None a keyword.  This prevents dumb users from
> assigning to it and screwing themselves, and can cause a slight
> speedup because using None avoids two dict lookups.
> - Any objections?

+1 but only if you use the standard mechanism for this:
warnings in 2.3, SyntaxError in 2.4.
> - Can somebody help me implement this?  I've got the parser changes
>   ready, but not the compiler changes.
> Believe it or not, Zope3 contains code that will break with this
> change: there are functions with a default argument of the form
> None=None as a speedup hack.  I think this is an argument *for* the
> change. :-)

Zope3 is not the only software using these kind of hacks
to work around the builtins lookups.

Marc-Andre Lemburg
CEO eGenix.com Software GmbH
Company & Consulting:                           http://www.egenix.com/
Python Software:                   http://www.egenix.com/files/python/