[Python-Dev] PEP 453 (pip bootstrapping) ready for pronouncement?

Brett Cannon brett at python.org
Thu Sep 26 16:00:15 CEST 2013

On Wed, Sep 25, 2013 at 7:15 PM, Donald Stufft <donald at stufft.io> wrote:

> On Sep 25, 2013, at 7:04 PM, Barry Warsaw <barry at python.org> wrote:
> > Another reason to oppose this is what I've heard quite often from people
> > regarding Python 2.7.  I've been told that many folks are actually really
> > happy with using 2.7 precisely because it extremely stable.  They don't
> have
> > to worry about their stuff breaking or incompatibilities cropping up,
> because
> > it *doesn't* change.  Python 2.7 is like a long-term maintenance
> release, with
> > guaranteed multi-year stability, and I think while that was unintended,
> it's a
> > *good* thing.  This PEP proposes to break that, and I'm loathe to give
> up that
> > good reputation for this particular feature.
> Maybe I'm just naive but can you expand on how adding a module that nothing
> else in the system imports (besides the installers; but you weren't
> arguing against
> adding this to the installers) would break someones use any other module?
> If
> they don't import it (which the vast bulk of people won't directly, nor at
> all during
> the operation of their applications) how does it's existence on the file
> system
> risk a breakage to their system?

I think Barry's worry is precisely the fact that users do silly things, so
having a new module suddenly show up in the stdlib can be a problem if
people start using the module. We could conceivably try and not expose the
module on sys.path somehow so that it can't be directly imported by anyone
who doesn't have any business using it unless they jump through some hoops
(e.g. stick it in Tools for Python 2.7 so the installers can get access but
it won't end up in the stdlib install).

Otherwise if Barry is worrying about a command-line tool being installed
for some users of Python 2.7 vs. not then I don't know what the worry is
because that happens on OS upgrades as well, let alone people who just
happen to have done the install themselves vs. not. People are already told
to install pip anyway, so if instructions point to ensurepip on PyPI as the
canonical way to install pip then whether it's installed or not is fine as
it will be mostly a no-op for 2.7.6 users and an actual install for others.
But by including it then it does simplify teaching scenarios and long tail
helps get pip out faster and more easily.
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