Fix the string representation of archetypes (#9297)

`Archetype.__str__` was broken at some point. This PR fixes it. It also
adds a (small) test.

Before:

```
rr.Points3D(
)
```

After:
```
rr.Points3D(
    positions=[[11.0, 2.0, 3.0], [2.0, 3.0, 2.0], [3.0, 2.0, 3.0], [2.0, 3.0, 2.0],
 [3.0, 2.0, 3.0], [2.0, 3.0, 2.0], [3.0, 2.0, 3.0], [2.0, 3.0, 2.0],
 [3.0, 2.0, 3.0], [2.0, 3.0, 2.0], [3.0, 2.0, 3.0], [2.0, 3.0, 3.0]],
    radii=[1.0, 2.0, 3.0]
)
```

Author: abey79

rerun_py/rerun_sdk/rerun/_baseclasses.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import re
 from collections.abc import Iterable, Iterator
 from typing import Generic, Protocol, TypeVar, runtime_checkable
 
@@ -201,18 +202,35 @@ class Archetype(AsComponents):
     """Base class for all archetypes."""
 
     def __str__(self) -> str:
-        cls = type(self)
+        from pprint import pformat
 
-        s = f"rr.{cls.__name__}(\n"
-        for fld in fields(cls):
-            if "component" in fld.metadata:
-                comp = getattr(self, fld.name)
-                datatype = getattr(comp, "type", None)
-                if datatype:
-                    s += f"  {datatype.extension_name}<{datatype}>(\n    {comp.to_pylist()}\n  )\n"
-        s += ")"
+        cls = type(self)
 
-        return s
+        def fields_repr() -> Iterable[str]:
+            for fld in fields(cls):
+                if "component" in fld.metadata:
+                    comp = getattr(self, fld.name)
+                    if comp is None:
+                        continue
+
+                    as_arrow_array = getattr(comp, "as_arrow_array", None)
+
+                    if as_arrow_array is None:
+                        comp_contents = "<unknown>"
+                    else:
+                        # Note: the regex here is necessary because for some reason pformat add spurious spaces when
+                        # indent > 1.
+                        comp_contents = re.sub(
+                            r"\[\s+\[", "[[", pformat(as_arrow_array().to_pylist(), compact=True, indent=4)
+                        )
+
+                    yield f"  {fld.name}={comp_contents}"
+
+        args = ",\n".join(fields_repr())
+        if args:
+            return f"rr.{cls.__name__}(\n{args}\n)"
+        else:
+            return f"rr.{cls.__name__}()"
 
     @classmethod
     def archetype_name(cls) -> str:

rerun_py/tests/unit/test_archetype_str.py

@@ -0,0 +1,100 @@
+from __future__ import annotations
+
+import pytest
+import rerun as rr
+
+
+@pytest.mark.parametrize(
+    ["archetype", "expected"],
+    [
+        [
+            rr.Transform3D(),
+            (
+                "rr.Transform3D(\n"
+                "  translation=[],\n"
+                "  rotation_axis_angle=[],\n"
+                "  quaternion=[],\n"
+                "  scale=[],\n"
+                "  mat3x3=[],\n"
+                "  relation=[],\n"
+                "  axis_length=[]\n"
+                ")"
+            ),
+        ],
+        [
+            rr.Transform3D(translation=[10, 10, 10]),
+            (
+                "rr.Transform3D(\n"
+                "  translation=[[10.0, 10.0, 10.0]],\n"
+                "  rotation_axis_angle=[],\n"
+                "  quaternion=[],\n"
+                "  scale=[],\n"
+                "  mat3x3=[],\n"
+                "  relation=[],\n"
+                "  axis_length=[]\n"
+                ")"
+            ),
+        ],
+        [
+            rr.Points2D(positions=[[0, 0], [1, 1], [2, 2]]),
+            "rr.Points2D(\n  positions=[[0.0, 0.0], [1.0, 1.0], [2.0, 2.0]]\n)",
+        ],
+        [
+            rr.Points2D(positions=[0, 0, 1, 1, 2, 2], radii=[4, 5, 6]),
+            "rr.Points2D(\n  positions=[[0.0, 0.0], [1.0, 1.0], [2.0, 2.0]],\n  radii=[4.0, 5.0, 6.0]\n)",
+        ],
+        [rr.Points2D.from_fields(), "rr.Points2D()"],
+        [
+            rr.Points3D(
+                [
+                    11,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    2,
+                    3,
+                    3,
+                ],
+                radii=[1, 2, 3],
+            ),
+            """\
+rr.Points3D(
+  positions=[[11.0, 2.0, 3.0], [2.0, 3.0, 2.0], [3.0, 2.0, 3.0], [2.0, 3.0, 2.0],
+    [3.0, 2.0, 3.0], [2.0, 3.0, 2.0], [3.0, 2.0, 3.0], [2.0, 3.0, 2.0],
+    [3.0, 2.0, 3.0], [2.0, 3.0, 2.0], [3.0, 2.0, 3.0], [2.0, 3.0, 3.0]],
+  radii=[1.0, 2.0, 3.0]
+)""",
+        ],
+    ],
+)
+def test_archetype_str(archetype: rr._baseclasses.Archetype, expected: str) -> None:
+    assert str(archetype) == expected