Improve error when raw2derived argument has no type

[Villtord]

Closes #1108

[coretl]

Please could I also have a similar test in test_multi_derived_signal where there are no type hints?

[Villtord]

Please could I also have a similar test in test_multi_derived_signal where there are no type hints?

I don't follow - if I add it there it will still test same DerivedSignalFactory which is already tested in test_single_derived

[coretl]

Please could I also have a similar test in test_multi_derived_signal where there are no type hints?

I don't follow - if I add it there it will still test same DerivedSignalFactory which is already tested in test_single_derived

Yes, but this captures the use case (need to check we get errors when invoked via DerivedSignalFactory as well as via derived_signal_r) rather than the implementation (they both use DerivedSignalFactory under the hood)

Also, would you mind if I let some AI loose on a code review of this PR?

[Villtord]

yay AI review! go for it.
So do you want to add in multi_derived_signal a new test that would use some child class of Transform with missing type hints for parameters in raw_to_derived() method?

[coretl]

So do you want to add in multi_derived_signal a new test that would use some child class of Transform with missing type hints for parameters in raw_to_derived() method?

yes please

yay AI review! go for it.

I'll trigger it, but I'll review it's review before you take any action on it...

[coretl]

@claude

[claude]

Claude finished @coretl's task in 2m 40s —— View job

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Code Review Complete

Summary

I've reviewed PR #1135 which improves error messages when raw_to_derived arguments lack type hints. The implementation is solid overall, with good error handling moved to the factory level as requested.

Key findings:

✅ Strengths:

• Type hint validation correctly moved to DerivedSignalFactory.__init__ for early error detection
• Good test coverage for the single-signal convenience function case
• Clean use of inspect.signature + get_type_hints to detect missing annotations

⚠️ Issues to address:

1. Missing test coverage: Per @coretl's request in comments, need test in test_multi_derived_signal.py testing DerivedSignalFactory directly (not just derived_signal_r convenience function)

2. Type hints: dict_wrapper() function lacks type annotations

3. Minor questions: Should _get_params_types_dict also filter out "cls" for classmethods?

Detailed feedback posted as inline comments on specific lines.

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[oliwenmandiamond]

This looks to be a big improvement of derived signal logic and error handling, thank you!

I would link my issue so it also closes that and update the PR title to be to make improvements to derived signal as we have moved beyond just fixing an error message now

[coretl]

Almost there