[Python-Dev] Python 4: don't remove anything, don't break backward compatibility

[Brett Cannon]

On Mon Mar 10 2014 at 11:50:54 AM, Victor Stinner <victor.stinner at gmail.com>
wrote:

> 2014-03-10 16:25 GMT+01:00 Stefan Richthofer <Stefan.Richthofer at gmx.de>:
> > I don't see the point in this discussion.
> > As far as I know, the major version is INTENDED to
> > indicate backward-incompatible changes.
>
> This is not a strict rule. I would like to follow Linux 3 which didn't
> break the API between Linux 2 and Linux 3.
>

I disagree. I don't think 3->4 will be as drastic as it was for 2->3, but I
view Python 4 as a chance to drop all deprecated APIs that we left in for
convenience in porting from Python 2 (e.g. the imp module). We can't put a
removal date as we can't really declare Python 2 dead for the whole
community. But when Python 4 does come out next decade I would like to say
that we have moved entirely beyond Python 2 as a team and thus don't turn
into Java and support deprecated code forever.


>
> > Even then, there is no need for 4.0; you can just have 3.10, 3.11 etc.
>
> The major version is sometimes seen as the age of a project. I propose
> to bump Python to version 4 because people understand that Python 4 is
> much better than Python 3 :-)


Sure, but you also understand 3.5 is better than 3.4. You're also making
the assumption that people are going to pick up on the fact that major
version shifts from Python are suddenly not a big deal, even though it is
still well known the shift from 2 to 3 was a big deal.


> Firefox changes its major version every
> 4 months or something like that.


Sure, but we are not about to do 4 month release cycles. Releasing that
often does make minor version numbers silly since they become double digits
so quickly. But since we are not shifting from our 18 month cycle we don't
have that issue; 15 years (typically) between a .0 and .9 release doesn't
really lead to a worry of exhausting reasonable minor version numbers.


> I suggest to wait less than 8 years
> for Python 4.
>

Why? What's special about 8 years?
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