For projects with more than a few packages, it is tedious to list all subpackages manually in setup.cfg.  There was once a find_packages in distutils2.util (copied from distribute), but when we moved away from setup.py it was removed (I don’t remember all the details).

A new field would be best if we could find a good name, or we could have special syntax in the existing packages field (like “packages = distutils2.*”).

+1 for the wildcard syntax.

Potential downside:

Say I have foo, foo.bar, and foo.tests.  I want to install foo and foo.bar, but not foo.tests.  Then I have to manually list all the packages I do want:

packages =
    foo
    foo.bar

That's fine, but one nice thing about find_packages is that it had an optional exclude argument. So maybe in addition to the wildcard syntax it couldn't hurt to add an exclude-packages option?  I don't think that would be too complicated.

Something similar for extension module sources would also be desirable.

IMO the best behavior would be to always recurse and have an option to exclude specific submodules.  When the Django devs want to package their code, they think about a Python package named django, docs and scripts, not about django, django.views, django.http, etc.  I proposed glob syntax or a new key to be conservative, but now I’ll add a third proposal:

packages = foo
packages-exclude = foo.spam

For a package foo with subpackages ham and spam, this would get foo and foo.ham.
Note that this was discussed on the fellowship ML two years ago but I don’t have the time to re-read the thread now.

(Why is it not named exclude-packages? 1) you can exclude single-file modules too with this option 2) it makes it clear that it’s a “sub-option” of packages)

About extension modules sources: good idea, but it should be its own feature request.