[Python-Dev] Re: redefining is

[Casey Duncan]

On Thu, 18 Mar 2004 10:51:02 -0800
Guido van Rossum <guido at python.org> wrote:

> > Indeed.  Of course, object() is mutable, so there is no proposal to
> > change the meaning of this program.  What I'm concerned about is
> > someone trying to do the same thing this way:
> > 
> > 	missing = 'missing'
> > 
> > 	if d.get('somekey', missing) is 'missing':
> > 		# it ain't there
> > 
> > This code contains a bug, but on an implementation that interns
> > strings that happen to look like identifiers, no test will detect
> > the bug.
> 
> I'm ready to pronounce.  The code is buggy.  There are good reasons to
> keep 'is' the way it always was.  The definition of 'is' ain't gonna
> change.  So be it.

So then: is is as is was ;^)

-Casey