Enable code analysis for plugins

[papercast-dev]

Issue: Pylance in VSCode is unable to recognize the dynamically imported plugins in the papercast package, leading to issues like "Go to definition" not working as expected for the installed plugins.

Example:

from papercast.processors import ArxivProcessor

In the above import statement, Pylance does not recognize the ArxivProcessor imported from the papercast.processors package after papercast-arxiv plugin is installed.

Possible solution:

• Change the plugin structure to one folder with four files: subscribers.py, processors.py, publishers.py, types.py Enforce file naming conventions for plugins #11 . Classes of each type should belong to each file. Maybe not a bad idea anyway.
• At install time for each plugin, generate stubs for each file, and place them in the corresponding submodule folders e.g. papercast/processors/stubs/. Alternatively, figure out a way to generate stubs for only a specific class from within a module using stubgen.
• Modify the __init__.pyi file to be able to import from papercast.processors import ArxivProcessor instead of from papercast.processors.arxiv_processor import ArxivProcessor.
  • Note: if we're ok with the messier import suggested in Change plugin imports to from papercast.types.plugin import Class #10 we might be able to skip this step?
• Make an init.pyi file with contents from .stubs import *
• Add a line to the papercast/processors/__init__.py:
  from papercast.processors import *

Notes:

• stubs/init.pyi is shared across plugins, maybe not ideal