[Distutils] What does it mean for Python to "bundle pip"?

[Paul Moore]

On 19 August 2013 15:28, Nick Coghlan <ncoghlan at gmail.com> wrote:

> > More specific response when I'm not half asleep.
>
> Donald sent me the preliminary draft last week, so I can share the short
> version of the proposal:
>
> * Bootstrap included in the standard library, executable as "python -m
> getpip". This ensures a clear distinction between files managed by the
> system installer (i.e. getpip) and those managed by pip (including pip
> itself)
> * Installs the bundled copy of pip by default, but has an option to do a
> network install of the latest from PyPI
> * Updates of the installed version use "pip install --upgrade pip" as
> normal
> * Bundled version inside getpip will be updated when pip is updated (so
> CPython maintenance releases may have newer versions of pip)
> * If you build from source, you need to run the bootstrap explicitly to
> get pip
> * Windows and Mac OS X installers will bootstrap the bundled pip by
> default (opt-out) with a network update option (opt-in)
>
> The following two points aren't in Donald's PEP yet, and are the main
> reason the initial draft wasn't published more widely:
>

Thanks for the update, Nick. I'll wait for Donald's comments and the
published version of the PEP before commenting in detail, but the following
points come to mind for me at least:

1. I would still like to see *some* clear statement of what the "guaranteed
interface" users can rely on is. Maybe I'm suggesting more than anyone else
is willing to commit to, but I *do* think that if we're suggesting that
there is now a "standard Python installer", we should give users some
indication of what it actually is. For example, I think it's reasonable as
a user to assume that "pip install foo" will work for the foreseeable
future - but not that (for example) "pip bundle" will.

2. We need to be careful to define exactly when and how the "pip" command
is present. Don't forget that on Windows, the "python" command is not on
PATH by default (and the existence of the launcher means that it really
doesn't need to be). I would suggest that we say something like "The pip
command will be installed alongside the python command, and will be
available when python is"[1]. We should also probably note that versioned
variants of pip will be provided matching the versioned copies of the
python command that are available (e.g., pip3/pip3.4 on Unix, maybe none at
all on Windows...). Unless of course we want to use a different scheme for
pip, in which case we need to agree on what that will be.

3. This also begs the question of whether pip.exe gets installed in the
"Scripts" subdirectory on Windows, as at present - if it does, we'll have
to be very careful indeed over how we word the instructions, as it's *easy*
for users to have python.exe on PATH but not have Scripts\pip.exe on there
:-(

Paul.

[1] I don't like that wording, but I can't find a better way of putting it
that covers all cases but isn't too wordy :-(
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