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

[Paul Moore]

On 10 March 2014 17:08, R. David Murray <rdmurray at bitdance.com> wrote:
> We had this discussion a bit ago, and my sense was that we tentatively
> decided that we were just going to deprecate and remove things as
> appropriate, irregardless of version number.  I used "4.0" in my
> message about 'U' as a shorthand for "some time after python2
> is no longer an issue".  Sorry for the confusion.  (That said, I
> do see some merit to doing some extra cleaning at the 4.0
> boundary, just for mental convenience.)

I have seen a number of postings recently pointing to things as "not
until Python 4000" or "not until Python 4.0" (yours was not one that I
noticed, actually, this is a more general point).

I do think it's a bad idea to start talking in terms of "the next big
compatibility break", even if *we* know there's no immediate plan.
People are very quick to pick up messages like "Now that Python 3 is
out of the way, the Python devs are talking about Python 4" which is
not a message we want to see getting traction.

I'm neither averse to, nor in favour of, a Python 4 compatibility
break in due course, but maybe we should avoid letting the idea take
hold this soon. Users are still concerned about the Python 3 change,
it wouldn't do any harm if they got the clear message "at least it's a
one-off exercise".

Paul