----- Original Message ----- From: "Guido van Rossum" firstname.lastname@example.org To: "Tim Peters" email@example.com Cc: firstname.lastname@example.org Sent: Friday, April 26, 2002 11:44 AM Subject: Re: [Python-Dev] Making None a keyword
... It needs to add 'None' as an alternative to all other places where currently NAME occurs.
Fudge. None makes no sense anywhere in, e.g.,
dotted_name: NAME ('.' NAME)*
global_stmt: 'global' NAME (',' NAME)*
but I suppose it has to be allowed for in 2.3 anyway else an existing
Yes, that's (alas) the point.
import None.None.None as None
would yield a SyntaxError instead of a warning.
def foo(a, None=None): if a is None: ...
I found 4 examples of this in Zope3 alone, and MAL has some too.
Note too that we can't change the generated code at all for 2.3 unless under the control of a new future statement, else existing None-abusing code could break.
A future statement makes no sense for this, so I guess all we can do in 2.3 is warn about use of None in all contexts except in expressions.
This is really too bad -- I wish we could decide to just break code (since it's a clean break) but apparently that's unacceptable to the users.
Wouldn't it be nice if there were a collection of programs (perhaps those owned by registered paranoids, but whatever) that you could use to get statistics about breakage under some syntax change?
Clearly extending this through to run-time would add a huge testing infrastructure that would need maintaining, but allowing people to add their own codes to the syntax-checker base might mollify them a bit about the prospect of future language change.
Call it the PythOnGuard (TM) database. :-) - if your programs would break you'll be mailed before it's committed to production.
Back to the yardwork ...
regards Steve --