[Distutils] PEP 439 and pip bootstrap updated

[Nick Coghlan]

(Oops, started this yesterday, got distracted and never hit send)

On 11 July 2013 11:09, Richard Jones <richard at python.org> wrote:
>
> On 11 July 2013 06:50, Paul Moore <p.f.moore at gmail.com> wrote:
> > I think "python -m pip" should be the canonical form (used in
documentation,
> > examples, etc). The unittest module has taken this route, as has timeit.
> > Traditionally, python-dev have been lukewarm about the -m interface,
but its
> > key advantage is that it bypasses all the issues around versioned
> > executables, cross-platform issues, the general dreadfulness of script
> > wrappers on Windows, etc, in one fell swoop.
>
> "python -m pip" does make the bootstrapping a more complex proposition
> - the stdlib would have to have something called "pip" that could be
> overridden (while it is actually *running*) by something installed in
> site-packages. Not easy.

I was thinking about that, and I'm wondering if the most sensible option
may be to claim the "getpip" name on PyPI for ourselves and then do the
following:

1. Provide "getpip" in the standard library for 3.4+ (and perhaps in a
2.7.x release)
2. Install it to site-packages in the "Python launcher for Windows"
installer for earlier versions

getpip would expose at least one function:

    def bootstrap(index_url=None, system_install=False):
        ...

And executing it as a main module would either:

1. Do nothing, if "import pip" already works
2. Call bootstrap with the appropriate arguments

That way, installation instructions can simply say to unconditionally do:

    python -m getpip

And that will either:

1. Report that pip is already installed;
2. Bootstrap pip into the user environment; or
3. Emit a distro-specific message if the distro packagers want to push
users to use the system pip instead (since they get to patch the system
Python and can tweak the system getpip however they want)

The 2.7 change would then be to create a new download that bundles the
Windows launcher into the Windows installer.

Users aren't stupid - the problem with the status quo is really that the
bootstrapping instructions are annoyingly complicated and genuinely
confusing, not that an explicit bootstrapping step is needed in the first
place.

Cheers,
Nick.




>
> Thanks everyone for your brilliant feedback and discussion - I look
> forward to being able to say something sensible about Windows in the
> PEP :-)


>
>
>
>      Richard


-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
On 11 July 2013 06:50, Paul Moore <p.f.moore at gmail.com> wrote:
> I think "python -m pip" should be the canonical form (used in
documentation,
> examples, etc). The unittest module has taken this route, as has timeit.
> Traditionally, python-dev have been lukewarm about the -m interface, but
its
> key advantage is that it bypasses all the issues around versioned
> executables, cross-platform issues, the general dreadfulness of script
> wrappers on Windows, etc, in one fell swoop.

"python -m pip" does make the bootstrapping a more complex proposition
- the stdlib would have to have something called "pip" that could be
overridden (while it is actually *running*) by something installed in
site-packages. Not easy.

Thanks everyone for your brilliant feedback and discussion - I look
forward to being able to say something sensible about Windows in the
PEP :-)


     Richard
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