Plugin System Tools

[pedro-psb]

Context and Problem Statement

The new project requires a plugin system to keep the core minimal.

What tools should we use to build a plugin system?

Decision Drivers

Open

Considered Options

• pluggy
• from scratch

Pros and Cons of the Options

Pluggy

Pluggy is the plugin library used by pytest, which is maybe the most well known plugin system in the python ecosystem.

about pluggy | pytest hooks examples

[Good]
- mature framework used by really big project in python ecosystem
- lighweight dependecy (it has a small codebase, no more than 1500 lines)
- seems easy and flexible to setup and use
 
[Bad]
- maybe it can limit some decisions?

From Scratch

Python entrypoints system can be used to build a plugin system alongside importlib.

entrypoints specifications | setuptools userguide on entrypoints

[Good]
- the system will be tailored to the library needs
 
[Bad]
- more error and bug prone
- more work to get it up and running

[pedro-psb]

I've read pluggy docs and about pytest hooks and I really think we should pick it.
It will streamline the modular architecture we want to build and provide good guidelines for this kind of library organization (mainly, pytest/pluggy docs and pytest codebase).

I don't think we need to reinvent the wheel here, and if for some reason we want/need to drop it, we'll have learned a lot about plugin system patterns.