[MNT]: Remove axis parameter from scales #29349
Description
Summary
For historic reasons, Scales take the axis as the first parameter. It's use is discouraged and none of our own scales actually use it at least since #12831.
To simplify our code, we should get rid of that parameter.
Proposed fix
Do we know whether
- downstream libraries add their own Scales via
register_scale()? - user will directly instantiate our own Scale classes?
If so we need the full deprecation machinery:
- Make
scale_factorywork with scales have or have not an initialaxisparameter. Either by try-except with/without this parameter or by introspecting the signature. - Introspect scale classes passed to
register_scaleand warn if they still have the axis argument. - Make all our scales work with/without the
axisparameter by adding a suitable decorator to their init functions. - Refactoring: Removing axis parameter from scales #29988
Otherwise, we can simplify the transition.
--
Edit: Both questions are yes, so we need the full deprecation mechanism.