[Python-Dev] Single- vs. Multi-pass iterability

[Guido van Rossum]

[me]
> > - There really isn't anything "broken" about the current situation;
> >   it's just that "next" is the only method name mapped to a slot in
> >   the type object that doesn't have leading and trailing double
> >   underscores.

[Patrick]
> I'm way behind on the email for this list, but I wanted to chime in
> with an idea related to this old thread. I know we want to limit the
> rate of language/feature changes for the business community. At the
> same time, this situation with iterators is proof that even the best
> thought out new features can still have a few blemishes that get
> discovered after they've been incorporated into Python proper. It's
> just terribly difficult to get anything "right" the very first time,
> and it would be nice to fix these blemishes sooner, rather than
> later.
> 
> So perhaps we need some sort of concept of a "grace period" on
> brand-new features during which blemishes can be polished off, even
> if the polishing breaks backward compatibility. After the grace
> period, breaking backward compatibility becomes a higher
> priority. Since we are talking about backward compatibility only as
> it relates to the brand-new features themselves, Python-In-A-Tie
> folks can avoid the issue altogether by not using the new features
> during the grace period.
> 
> Would something like this be an acceptable compromise?

I guess we could explicitly label certain features as experimental in
2.3.  I don't think we can interpret 2.2 like this retroactively --
while the new type stuff was labeled experimental at some point, the
iterators and generators were not, and the new type stuff was pretty
much fixed by releasing 2.2.1 (and by declaring 2.2 the tie-wearing
Python).

--Guido van Rossum (home page: http://www.python.org/~guido/)