[FR] Accept dynamic description to come from an attribute.

What's the problem this feature will solve?

It would make it possible to keep the package description in sync with the package docstring.

Describe the solution you'd like

I propose to accept the following directives:

setup.cfg

description = attr: mypackage.__doc__

pyproject.toml

[tool.setuptools.dynamic]
description = {attr = "mypackage.__doc__"}

Alternative Solutions

The current option is either to rely on setup.py or to manually keep the __doc__ and description in sync which is prone to error.

Additional context

I think this feature would be fairly easy to implement, as it is mostly a copy-paste from version. I tried to implement it myself, but I did not find what to do with the generated _validate_pyproject code.

Moreover, this feature is found in flit.

Code of Conduct

• I agree to follow the PSF Code of Conduct

Start by comparing the existing version handling with the generated _validate_pyproject code, using the setup.cfg and pyproject.toml examples in the issue as the target configuration forms. Done means accepting description values from package attributes in both formats and validating the new pyproject.toml syntax consistently.