Raise an Error When Computed Field Overrides Field

[sydney-runkle]

Change Summary

• If a computed_field is defined in a subclass such that it overrides a field from a superclass, a ValueError is raised.

Related issue number

fix #7250

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
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[adriangb]

Approving since this error is at least less confusing than the current behavior. We can continue the discussion in #7250 if erroring doesn't seem like an acceptable approach.

[silky]

It's moderately unfortunate that this behaviour is not available when it is available with pure dataclasses (despite the mypy warning.)

Is there any thoughts of a work-around? I.e. to override an inheritied property; with a computed field or otherwise?

-- Edit:

A related observation is that if you merely removed the @computed_field tag for the field of interest, you no longer get a warning, you merely get that your re-defined field is never evaluated; which is probably still at least a bug. I.e. the central behaviour that isn't supported is this style of overriding!