18. Forbid Private Member Access in Production Code

Date: 2024-07-02

Status

Accepted

Context

Most programming languages forbid access to private member variables at compile time to guarantee encapsulation. Python only does this by convention. Ruff now provides a rule (SLF001) that forbids it. See https://github.com/DiamondLightSource/python-copier-template/issues/154 for further discussion.

Decision

We will enable SLF001 for the src directory but not the tests directory, as we want to keep production code clean without raising the barrier to entry for writing tests.

Consequences

Any private member access in src will cause CI to fail, the ultimate override of noqa remains available.