How to build locally & with caching?

[takluyver]

Is there a recommended way to quickly build a package locally, as fast as possible, for testing changes? With setuptools, I've done something like this:

python setup.py build --build-lib build/for-test
PYTHONPATH=build/for-test pytest

Using pip install --no-build-isolation . takes 4-5 seconds even with no changes, which is OK if there's nothing better, but it seems like it should be possible to go faster than that. Using the meson command can be much quicker, but meson compile doesn't copy the .py files into its build folder, and meson install wants to create a site-packages/python3.12 style layout, which in this case isn't what I want.

Editable installs work nicely if you're only changing pure Python code, but I'd like to have a solution for changing Cython code with a fast build & test loop as well.

[rgommers]

Hey @takluyver, good question. A few options:

• Editable installs do work, and are automatically rebuilding also Cython (and C, etc.) code if and only if source files are changed.
• A manual meson compile && meson install does work without touching site-packages if you configured initially with meson setup builddir --prefix=$PWD/build-install or something like that.
• https://github.com/scientific-python/spin/ UX provides a nice UX for essentially the manual steps above plus setting PYTHONPATH etc.

I'd recommend either using editable installs directly, or spin. Both should do what you want.

[takluyver]

Thanks @rgommers ! I've taken spin for a spin, it looks promising so far. 👍