This post here is to review the status of the sdist as part of scikit-image in light of recent developments in how python is now packaged in late 2019.

A few recent developments have been:

1. The removal of pyproject.toml Remove pyproject.toml, backport of (#3688) #3914
   • This was done because pyproject.toml would create a fresh environment, which could result building scikit-image with a newer version of numpy than the user had installed in their current environment. This would result in strange and confusing bugs.
2. The removal of the cython md5 hashing Remove cython md5 hashing since it breaks the build process #3254
   • Unfortunately this only hashed the pyx (implementations) and not the pxd (declartions). This could cause the generation of files with different headers which could cause segfaults when developing cython code.

In the latest 0.16.0 release, we had a hiccup due to an old version of cython being used to generate the c files released in the sdist. @stefanv mentionned that we should consider not shipping c files with the sdist.

Numpy actually recommends very aggressively new versions of cython for their downstream packagers to use. We can maybe consider moving up our pinning to bleeding edge???

The major change in the python community has been the ease at which users on the major platforms can install scikit-image. Wheels are provided for all our core dependencies, and this greatly reduces the complexity of installing (and building from source) scikit-image.

To summarize:

• Should we move to bleeding edge cython?
• Should we remove pregenerated c files from the sdist?