Add bootstrap script/wheel module for flit_core

[jameshilliard]

Improved version of #481 based on comments here.

Details from help:

$ python -m flit_core.wheel --help
usage: wheel.py [-h] [--srcdir SRCDIR] [--outdir OUTDIR]

options:
  -h, --help            show this help message and exit
  --srcdir SRCDIR, -s SRCDIR
                        source directory (defaults to current directory)
  --outdir OUTDIR, -o OUTDIR
                        output directory (defaults to /Users/jameshilliard/flit/flit_core/dist)

$ python bootstrap.py --help
usage: bootstrap.py [-h] {build,install} ...

positional arguments:
  {build,install}

options:
  -h, --help       show this help message and exit

$ python bootstrap.py build --help
usage: bootstrap.py build [-h] [--outdir OUTDIR]

options:
  -h, --help            show this help message and exit
  --outdir OUTDIR, -o OUTDIR
                        output directory (defaults to /Users/jameshilliard/flit/flit_core/dist)

$ python bootstrap.py install --help
usage: bootstrap.py install [-h] [--wheeldir WHEELDIR] [--installdir INSTALLDIR]

options:
  -h, --help            show this help message and exit
  --wheeldir WHEELDIR, -w WHEELDIR
                        wheel dist directory (defaults to /Users/jameshilliard/flit/flit_core/dist)
  --installdir INSTALLDIR, -i INSTALLDIR
                        installdir directory (defaults to /Users/jameshilliard/flit/venv/lib/python3.10/site-packages

[FFY00]

Ah, I think I missed something, shouldn't this be installed? If so, this should live under the flit_core module, and accessible via python -m flit_core.bootstrap.

I will look at this in more detail later.

[jameshilliard]

Ah, I think I missed something, shouldn't this be installed?

Only the wheel builder is installed since the bootstrap.py installer is only designed to install flit_core itself, it's expected that installer be used to install wheels built using python -m flit_core.wheel. This should work for bootstrapping since installer only depends on flit_core.

[takluyver]

Thanks for this. In the interests of keeping the extra script as simple as possible, and minimising coupling between the script and the internals of flit_core, I'd like to have the script only do installation, and use python -m flit_core.wheel directly to build a wheel. From what we've discussed this is the same command you'll use to build wheels for a few subsequent packages (e.g. installer, tomli), so I don't think it should be a problem to use it for flit_core itself as well.

I know what I want this to look like, so I hope you won't mind if I just make the changes directly rather than asking you to do them.

[takluyver]

OK, I hope this works for you.

I've got rid of the globbing inside the script - if you know there's only one suitable wheel in a directory, you can always use dist/flit_core-*.whl in a script calling it. And I've got rid of the fallback to building a wheel, because I want this to do just one simple thing, not have different code paths. You've mentioned in the past that you separate build & install steps, so I assume you don't need one script combining them (and if anyone does, it should be easy to write that themselves).

[jameshilliard]

In the interests of keeping the extra script as simple as possible, and minimising coupling between the script and the internals of flit_core, I'd like to have the script only do installation, and use python -m flit_core.wheel directly to build a wheel.

Yeah, I don't think that should be an issue, I had just attempted to preserve the combo build+install option from #481 but for our use case where we do build+install stage separation a combo build+install is not actually needed.

I know what I want this to look like, so I hope you won't mind if I just make the changes directly rather than asking you to do them.

OK, I hope this works for you.

Yeah, I think this should work for us.

[takluyver]

Great, thanks. I've updated the bootstrapping doc. I'll give it another day or two in case other maintainers want to look at it, but otherwise I think this can go in.

[blink1073]

LGTM!