face_tracking example fails with new AnnotationContext implementation

[abey79]

Describe the bug

It looks like rr.ClassDescription() now requires and argument that wasn't formerly required.

❯ python examples/python/face_tracking/main.py 
INFO: Created TensorFlow Lite XNNPACK delegate for CPU.
Traceback (most recent call last):
  File "/Users/hhip/src/rerun/examples/python/face_tracking/main.py", line 428, in <module>
    main()
  File "/Users/hhip/src/rerun/examples/python/face_tracking/main.py", line 422, in main
    run_from_video_capture(args.camera, args.max_dim, args.max_frame, args.num_faces)
  File "/Users/hhip/src/rerun/examples/python/face_tracking/main.py", line 311, in run_from_video_capture
    detector = FaceDetectorLogger(video_mode=True)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/hhip/src/rerun/examples/python/face_tracking/main.py", line 119, in __init__
    rr.ClassDescription(keypoint_connections=[(0, 1), (1, 2), (2, 0), (2, 3), (0, 4), (1, 5)]),
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/hhip/src/rerun/rerun_py/rerun_sdk/rerun/_rerun2/datatypes/class_description.py", line 53, in __init__
    classdescription_init(self, *args, **kwargs)
TypeError: classdescription_init() missing 1 required positional argument: 'info'

[abey79]

This example is likely broken as well: https://www.rerun.io/docs/reference/data_types/annotation_context#connections-example

[emilk]

why isn't mypy catching this?

[abey79]

why isn't mypy catching this?

Custom init overrides are untyped unfortunately. That's one of the major eyesore of the codegen's python SDK in its current state.

[emilk]

I believe this was introduced in https://github.com/rerun-io/rerun/pull/2895/files#diff-e4f8d37313c7297c2faac15acce4fa15501d41993f79b717e817213f8c20764eR30

struct ClassDescription has a pub info: crate::datatypes::AnnotationInfo, which before used the AnnotationInfo::default():

#[derive(Clone, Debug, Default, Eq, PartialEq)]
pub struct AnnotationInfo {
    /// `ClassId` or `KeypointId` to which this annotation info belongs.
    pub id: u16,

    /// The label that will be shown in the UI.
    pub label: Option<crate::datatypes::Label>,

    /// The color that will be applied to the annotated entity.
    pub color: Option<crate::datatypes::Color>,
}

Our new code-gened ClassDescription (part of the annotation context) now require the user to supply an AnnotationInfo whereas before I believe this was set to AnnotationInfo::default if omitted (giving an id=0). I’m not sure what should be the behavior here, as I find the whole annotation context very complicated 😬

Does it make sense to have AnnotationInfo::default, or is it a footgun?
Is examples/python/face_tracking/main.py wrong not to include an info? If it should be included, what should it be set to?

Ideally I would like to give info a default value in rerun_py/rerun_sdk/rerun/_rerun2/datatypes/_overrides/annotation_context.py, but I can't because AnnotationInfoLike requires a label and a color, even though those fields are nullable.

Is attr.python.aliases in crates/re_types/definitions/rerun/datatypes/annotation_info.fbs wrong? It seems to force users to select a label and color, even though they are nullable. But perhaps it is the codegen that is wrong, missing the nullabel in this case?

[emilk]

This is not a problem on 0.8.0, so no need for a fix for 0.8.1