Feature: pip-installable MDSplus "local" wheel - #3078
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Build a small MDSplus wheel, at install time, into <prefix>/python/wheelhouse.
Its only payload is a MDSplus.pth (+ a _mdsplus_bootstrap.py it imports) that
points a Python environment at this install's python/MDSplus package -- a
redirect, not a copy. Gated behind ENABLE_PYTHON_LOCAL_WHEEL (default ON).
Why a wheel instead of PYTHONPATH=$MDSPLUS_DIR/python: setting PYTHONPATH makes
`import MDSplus` work but leaves the environment with no record that MDSplus is
installed. Shipping it as a real distribution means:
- MDSplus's dependencies (numpy, ...) are pulled in automatically by the
resolver instead of being wrangled out of band;
- it installs into a venv / uv-managed env and just works;
- other pyprojects can depend on `MDSplus` and resolve it from the local
wheelhouse (pip/uv --find-links, or a flat uv index) -- no per-project or
per-CI PYTHONPATH plumbing;
- being a redirect, it always imports the MDSplus that matches the installed
C libraries.
At import time the bootstrap back-determines MDSPLUS_DIR from the install the
wheel was built for and sets up its environment -- convenient for testing:
- startup is minimal: set MDSPLUS_DIR to the baked install (or $MDSPLUS_DIR
if it was relocated) and prepend its python/ to sys.path;
- on the first `import MDSplus`, if MDSPLUS_DIR was rewritten or the env is
not sourced, a one-shot import hook sources the install's setup.sh (honoring
local envsyms) and merges the resulting environment;
- it never spawns a process at plain startup and can never break the
interpreter; MDSPLUS_LOCAL_WHEEL_DISABLE=1 turns it off.
The wheel is assembled by make_wheel.py using only the standard library (no
build backend, no pip build isolation, no network); its dependencies and
metadata are copied from python/MDSplus/pyproject.toml so tooling reports the
genuine package info.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Carry the python-local-wheel feature (MDSplus/mdsplus#3078) as a patch: a redirect wheel is built into <prefix>/python/wheelhouse at install time (ENABLE_PYTHON_LOCAL_WHEEL), replacing the formula-built copy wheel, so venv/uv environments can `pip install --find-links` it. Test block: pin the venv to brewed python@3.13 (a uv-managed python3.13 earlier on PATH ships a pip too old for Homebrew's release-cooldown --uploaded-prior-to=P1D flag), assert the .pth redirect actually installs, and only exact-match the version on stable builds (Homebrew's HEAD-<sha> label never equals MDSplus's release tag). Revision bump so existing installs pick up the wheelhouse. Closes #34. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Darren Garnier <dgarnier@reinrag.net>
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Testing this patch with homebrew here: https://github.com/dgarnier/homebrew-plasma/releases/tag/mdsplus-alpha_release-7-160-2_1 can install on macOS with: |
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As promised in the discussion about #3074, I had an idea for a re-direct python wheel.
The idea is just build a wheel that does the minimum and make a .pth. Claude and
I got together and got a little more clever than that, so we don't need to run python
packaging tools during the build.
An optional build step (
ENABLE_PYTHON_LOCAL_WHEEL, default on, easy to turnoff) that writes a small MDSplus wheel into
<prefix>/python/wheelhouse. Thewheel is a redirect, not a copy: its only payload is a
MDSplus.pththat addsthis install's
python/MDSplusto a Python environment.This is a nice-to-have, not a need-to-have. The usual
PYTHONPATH=$MDSPLUS_DIR/pythonworks fine for most uses. This method adds some other niceties.
pip install MDSplus --find-links $MDSPLUS_DIR/python/wheelhouseinto a venv pulls innumpyautomatically, which a barePYTHONPATHdoes not;MDSplusas a dependency and resolve it from thewheelhouse (
pip/uv --find-links) rather than wiringPYTHONPATHin eachproject or CI job.
Kept deliberately small and self-contained so it's cheap to maintain or ignore:
one
python/local_wheel/subdir, a stdlib-onlymake_wheel.py(no buildbackend, no network), and the
.pth/bootstrap. Nothing else depends on it, andit's behind a flag. Metadata and dependencies are copied from
python/MDSplus/pyproject.tomlsopip showreports the real package.Behavior of the redirect at runtime:
MDSPLUS_DIRto the install the wheel was builtfor (or
$MDSPLUS_DIRif it was relocated) and prepend itspython/tosys.path;import MDSplus, if needed, a one-shot hook sources thatinstall's
setup.shto populate the environment (handy for pointing athrowaway venv at a specific build when testing);
interpreter, and
MDSPLUS_LOCAL_WHEEL_DISABLE=1disables it.Draft while it gets more testing. See
python/local_wheel/README.mdfor usage.