Why do some packages provide wheels for Linux platform?
Why shouldn't they, as long as source distributions are available as well? :)
Your question is not clear. If you meant
Why do some packages provide platform-specific wheels for Linux platform instead of platfom-independent ones?
then take a look at this question and its answers. If not, please clarify your question.
On Ubuntu: I should get the source distribution of the package BUT in some cases I get wheels.
Try using:
pip install --no-binary :all: somepackage
This should make pip download a source distribution if it exists on PyPI. I don't know why there are no source packages for PyQt5 on PyPI, probably because they are not installable with pip and need a whole toolchaing for compilation.
Is this okay? Providing binaries instead of the source?
It's okay as long as you provide both binaries and the source. I suggest you doing so.
Why I cannot provide wheels?
Try python setup.py bdist_wheel. You need to install wheel package (on PyPI) to make it work. If your package supports both Python 2 and 3 and contains no C extensions, append the --universal option to make a "universal wheel".
Replace bdist_wheel with sdist to make a source distribution. It will create an archive in dist directory.
sdist creates the archive of the default format for the current platform. The default format is a gzip’ed tar file (.tar.gz) on Unix, and ZIP file on Windows.
You can specify as many formats as you like using the --formats option, for example:
python setup.py sdist --formats=gztar,zip
to create a gzipped tarball and a zip file
(Quote from https://docs.python.org/3/distutils/sourcedist.html)
More info about packaging and wheels is available here: https://packaging.python.org/distributing/#packaging-your-project
