Dynamic Metadata

[RossBoylan]

Goal

.constants.json defines a number of metadata fields. The package reads it at runtime to populate information about the module, and hatch reads it at build time to describe the package. How can I get hatch to do that?

Background

I am trying to update gnumeric-py which uses distutils for setup; it uses setup.py which in turn invokes a small program to read the JSON file and set the metadata. I could simply copy the metadata to pyproject.toml (after adjusting the syntax), but then it would not be available at run time. Some think that's fine, but I'm trying to minimize the changes I make.

An Existing Solution?

This is the same kind of thing hatch already does for version, and so I assume the machinery is there. But I can't figure out how to use it. There is a custom metadata hook that seems relevant, but I can't tell how I'm supposed to use it. I think it's designed to load a plugin dynamically, so that I would then need to write the plugin....

The regex source might be suitable, if it could be applied to fields other than version. But my case is different because ideally one file would update multiple metadata fields.

[ofek]

Example: https://github.com/facelessuser/Rummage/blob/a752c4bdd9bd10b537b50394bafc2368422705e9/hatch_build.py#L29-L59

[RossBoylan]

Thank you. I don't see an explicit reference to hatch_build.py in pyproject.toml--is it just imported automatically by hatch?
And does the empty section [tool.hatch.metadata.hooks.custom] activate the CustomMetadataHook? Does the name need to be CustomMetadataHook?

[ofek]

Sorry for the lack of tutorials. Yes that section activates the hook and that name is the default for the file https://hatch.pypa.io/latest/plugins/metadata-hook/custom/#options. The class name is irrelevant, you can name it however you like!

After you get it working would you mind writing a How-to section in the docs so that others may benefit from what you learn? Then in future I can just refer people to that (if they already didn't read your page).

[RossBoylan]

I wrote a How-to and created a draft PR #1285