Datasette currently has a few API internals that return sqlite3.Row objects. I was thinking about how this might work in the future - if Datasette ever expands beyond SQLite (plugin-provided backends for PostgreSQL and DuckDB for example) I'd want a way to return data from other stores using objects that behave like sqlite3.Row but are not exactly that class.
How would they add runtime checking without breaking all existing code?
But I think warning people is a good start, because those checks can be added to your CI pipeline and reject any incoming code that contains warnings. That way you can enforce type checking for a subset of modules and keep backwards compatibility.
By making it opt-in. But that’s not much different from static typing then, except that it won’t actually work when you screw up typing