SciPy 1.7 builds as zipped egg, ruining imports

When building SciPy 1.7.1 from source I end up with a broken build which is unable to import e.g. scipy.optimize, as described in this Stack Overflow post. The installation finished without errors, though. I can (and have for years) successfully build SciPy 1.6, 1.5, 1.4. It turns out that SciPy 1.7 (at least on my system, for whatever reason) installs as a zipped Python egg to site-packages, rather than as a directory.

Solution

Supplying zip_safe = False to setuptools.setup() in setup.py does the trick. That is, zip_safe should be added to the metadata variable. I wonder why this is not there already. Is it ever safe to build SciPy as a zipped archive? Looking at NumPy’s setup.py, we indeed find zip_safe=False inside metadata.

Version information:

Python 3.9.6 SciPy 1.7.1 NumPy 1.21.1 Cython 0.29.24 gcc 9.3.0 Linux Mint, kernel 5.11.1

[rgommers]

Here it says

Yeah, sorry about that - we have a lot of build docs, and they’re always in need of improvements. There’s too many ways to build and set up environments.

Is this the proper way?

Yes, that’s good. Or even simpler: pip install . -v (the -v so you see the build log) does it all in one go.

Unlike build, bdist_wheel does not allow the --fcompiler option. I would like to be able to supply this to the build process

Ah yes, that’s a problem. In such cases I’m afraid you still need setup.py build or setup.py build_ext.

How do I (programmatically) know where the .whl file ends up and what it is called? Is it guaranteed to end up as the only file in the ./dist directory?

Yes, that is guaranteed.

[jmd-dk]

@rgommers I guess this issue is solved, but now I have questions for my own sake. 🙂

python setup.py install

Obligatory comment: don’t do this, build a wheel instead and install that with pip. setup.py install is unsupported.

Here it says

python setup.py build
python setup.py install

is the way to go. How do I instead build a wheel and install this with pip? I find that I can successfully do

python setup.py bdist_wheel
pip install /path/to/freshly/build/wheel.whl

even without adding zip_safe=False. Is this the proper way? If so I have two minor problems:

1. Unlike build, bdist_wheel does not allow the --fcompiler option. I would like to be able to supply this to the build process.
2. How do I (programmatically) know where the .whl file ends up and what it is called? Is it guaranteed to end up as the only file in the ./dist directory?