Consider type hints and a checker

[jmccarten-wetafx]

A number of times we inject code and exceptions to check typing - e.g. during read we check IO objects are paired with appropriate artifacts. These checks could be replaced with type hints and a pass by mypy.

[saeedya]

Hi, I'd like to work on this issue.

Before starting, I have a few questions:

1. Should we add type hints incrementally (one module at a time) or all at once?
2. Should mypy be added to the CI pipeline as part of this?
3. Which module would you suggest starting with?

[jmccarten-wetafx]

Hi Saeed, I think one module at a time would be the best way, I would also hold off a week or two as we are about to push a second large drop to the develop branch from Weta, we're then hoping to move to a much more frequent update cadence. If you do it before then we'll like have a complex merge situation.

If you want to get started on it now - anything related to the project CI/CD system will be likely untouched by the drop, so invoking the check in the pipeline will be a good start.

After the drop, regarding modules - starting from the root of RMTC and moving to the leaves would be most impactful - so System classes, then down.

Cheers,
John

[saeedya]

Thanks John! I'll wait for the drop before starting on the type hints. In the meantime, I'll add mypy to the CI pipeline as you suggested.

[saeedya]

After testing mypy, there are 35 errors related to the property setter pattern used across the code-base. I'll hold off on adding mypy to CI until after the upcoming drop and type hints are added as discussed.