[Python-ideas] install pip packages from Python prompt

[Erik Bray]

On Sun, Oct 29, 2017 at 8:45 PM, Alex Walters <tritium-list at sdamon.com> wrote:
> Then those users have more fundamental problems.  There is a minimum level
> of computer knowledge needed to be successful in programming.  Insulating
> users from the reality of the situation is not preparing them to be
> successful.  Pretending that there is no system command prompt, or shell, or
> whatever platform specific term applies, only hurts new programmers.  Give
> users an error message they can google, and they will be better off in the
> long run than they would be if we just ran pip for them.

While I completely agree with this in principle, I think you
overestimate the average beginner.  Many beginners I've taught or
helped, even if they can manage to get to the correct command prompt,
often don't even know how to run the correct Python.  They might often
have multiple Pythons installed on their system--maybe they have
Anaconda, maybe Python installed by homebrew, or a Python that came
with an IDE like Spyder.  If they're on OSX often running "python"
from the command prompt gives the system's crippled Python 2.6 and
they don't know the difference.

One thing that has been a step in the right direction is moving more
documentation toward preferring running `python -m pip` over just
`pip`, since this often has a better guarantee of running `pip` in the
Python interpreter you intended.  But that still requires one to know
how to run the correct Python interpreter from the command-line (which
the newbie double-clicking on IDLE may not even have a concept of...).

While I agree this is something that is important for beginners to
learn (e.g. print(sys.executable) if in doubt), it *is* a high bar for
many newbies just to install one or two packages from pip, which they
often might need/want to do for whatever educational pursuit they're
following (heck, it's pretty common even just to want to install the
`requests` module, as I would never throw `urllib` at a beginner).

So while I don't think anything proposed here will work technically, I
am in favor of an in-interpreter pip install functionality.  Perhaps
it could work something like this:

a) Allow it *only* in interactive mode:  running `pip(...)` (or
whatever this looks like) outside of interactive mode raises a
`RuntimeError` with the appropriate documentation
b) When running `pip(...)` the user is supplied with an interactive
prompt explaining that since installing packages with `pip()` can
result in changes to the interpreter, it is necessary to restart the
interpreter after installation--give them an opportunity to cancel the
action in case they have any work they need to save.  If they proceed,
install the new package then restart the interpreter for them.  This
avoids any ambiguity as to states of loaded modules before/after pip
install.



> From: Stephan Houben [mailto:stephanh42 at gmail.com]
> Sent: Sunday, October 29, 2017 3:43 PM
> To: Alex Walters <tritium-list at sdamon.com>
> Cc: Python-Ideas <python-ideas at python.org>
> Subject: Re: [Python-ideas] install pip packages from Python prompt
>
>
>
> Hi Alex,
>
>
>
> 2017-10-29 20:26 GMT+01:00 Alex Walters <tritium-list at sdamon.com>:
>
>         return “Please run pip from your system command prompt”
>
>
>
>
>
> The target audience for my proposal are people who do not know
>
> which part of the sheep the "system command prompt" is.
>
> Stephan
>
>
>
>
>
> From: Python-ideas
> [mailto:python-ideas-bounces+tritium-list=sdamon.com at python.org] On Behalf
> Of Stephan Houben
> Sent: Sunday, October 29, 2017 3:19 PM
> To: Python-Ideas <python-ideas at python.org>
> Subject: [Python-ideas] install pip packages from Python prompt
>
>
>
> Hi all,
>
> Here is in somewhat more detail my earlier proposal for
>
> having in the interactive Python interpreter a `pip` function to
>
> install packages from Pypi.
>
> Motivation: it appears to me that there is a category of newbies
>
> for which "open a shell and do `pip whatever`" is a bit too much.
>
> It would, in my opinion, simplify things a bit if they could just
>
> copy-and-paste some text into the Python interpreter and have
>
> some packages from pip installed.
>
> That would simplify instructions on how to install package xyz,
>
> without going into the vagaries of how to open a shell on various
>
> platforms, and how to get to the right pip executable.
>
> I think this could be as simple as:
>
>   def pip(args):
>       import sys
>       import subprocess
>       subprocess.check_call([sys.executable, "-m", "pip"] + args.split())
>
>       print("Please re-start Python now to use installed or upgraded
> packages.")
>
> Note that I added the final message about restarting the interpreter
>
> as a low-tech solution to the problem of packages being already
>
> imported in the current Python session.
>
> I would imagine that the author of package xyz would then put on
>
> their webpage something like:
>
>   To use, enter in your Python interpreter:
>
>      pip("install xyz --user")
>
> As another example, consider prof. Baldwin from Woolamaloo university
>
> who teaches a course "Introductory Python programming for Sheep Shavers".
>
> In his course material, he instructs his students to execute the
>
> following line in their Python interpreter.
>
>    pip("install woolamaloo-sheepshavers-goodies --user")
>
> which will install a package which will in turn, as dependencies,
>
> pull in a number of packages which are relevant for sheep shaving but
>
> which have nevertheless irresponsibly been left outside the stdlib.
>
> Stephan
>
>
>
>
>
>
>
>
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