This avoids certain problems related to the entire repo root appearing
on the import path, usually when running Python/pip from the repo root
or when using an editable install.
As of setuptools 46.4.0, this extracts the attribute value statically
using the ast module, if possible. This allows it to work properly even
if the attribute is stored in a file that cannot be imported at setup
time (e. g. because of dependencies that might not be installed yet).
Reading the version number using attr: rsrcfork.__version__ will no
longer work properly if rsrcfork has non-stdlib dependencies at import
time, because setuptools needs to be able to import rsrcfork and read
the version number before the dependencies are installed.
As a workaround, our setup.py now manually parses the version number
from rsrcfork/__init__.py using the ast module.
This caused normal installs (i. e. without --editable) of this library
to not include the rsrcfork.compress subpackage, and made everything
unusable as a result. Oops.
Altough this library is OS-independent, it is specifically relevant to
Classic Mac OS and OS X, and provides some extra functionality on OS X
(reading actual resource forks, instead of resource fork data stored in
data forks/regular files).
"Topic :: Software Development :: Libraries :: Python Modules" appears
to be specifically for libraries used to develop Python modules, and
not for Python modules in general. A few more appropriate classifiers
have been added instead.
dgelessus