Replacement for %pip

Problem

1. The %pip that comes with IPython doesn’t work with jupyterlite as there is no shell.
2. ipywidgets is not included, and requires using await micropip.install(). This is confusing for new users because it uses asyncio, and because it isn’t pip

Proposed Solution

If we override %pip, then we can install ipywidgets (and other packages) without having to use asyncio and micropip. This could make many notebooks 100% identical to their regular IPython brothers.

Here is an implementation (although this is my first asyncio code):

from IPython.core.magic import register_line_magic
from IPython.core import magic_arguments
import asyncio

IN_BROWSER = None
try:
    import micropip
    IN_BROWSER = True
except ImportError:
    IN_BROWSER = False

if IN_BROWSER:
    async def pip_install(package):
        try:
            await micropip.install(package)
            return "    Success! Installed %r" % package
        except Exception as exception:
            return "    Failed installing %r: %s" % (package, exception)

    @register_line_magic
    @magic_arguments.magic_arguments()
    @magic_arguments.argument('-q', '--quiet', help='Give less output.', action='store_true')
    @magic_arguments.argument('command', help="Install.", type=str)
    @magic_arguments.argument('packages', nargs="+", type=str, help='Packages to install.')
    def pip(line):
        args = magic_arguments.parse_argstring(pip, line)
        if args.command == "help":
            print("usage: %pip install package1 package2 ...")
        elif args.command == "install":
            print("Installing %s..." % args.packages)
            loop = asyncio.get_running_loop()
            for package in args.packages:
                task = loop.create_task(pip_install(package))
                task.add_done_callback(
                    lambda t: print(t.result()))
        else:
            print("error: command should be: `install`")

If this is a viable solution, where would this code go?

Output examples:

[bollwyvl]

This is a good direction, though given how thin the wrapper there is around pip… it supports a lot of options, and a lot of them will be nonsense in this context, as micropip sure as shooting won’t support all of them.

@martinRenou @madhur-tandon thoughts on the relationship to #216, and specifically, where to land this?

[bollwyvl]

For a potential solution: went the other way on this on #832, rewriting %pip to await __import__('piplite').install.