Readable nominal type captions in shared previews

src/formbridge/forms/ui_utils.py

@@ -5,6 +5,7 @@
 """
 
 import logging
+import re
 from dataclasses import dataclass
 from enum import Enum
 from typing import Any
@@ -21,7 +22,13 @@ class FieldDisplayText:
 
     @classmethod
     def from_field_name(cls, name: str) -> "FieldDisplayText":
-        display_name = name.replace("_", " ").title()
+        # Labels accept both parameter_names and nominal ClassNames.
+        words = re.sub(r"([A-Z]+)([A-Z][a-z])", r"\1 \2", name)
+        words = re.sub(r"([a-z0-9])([A-Z])", r"\1 \2", words)
+        display_name = " ".join(
+            word if word.isupper() else word.title()
+            for word in words.replace("_", " ").split(" ")
+        )
         return cls(
             display_name=display_name,
             field_label=f"{display_name}:",

src/formbridge/utils/preview_formatters.py

@@ -9,6 +9,8 @@
 
 from objectstate import ParameterOwner
 
+from formbridge.forms.ui_utils import FieldDisplayText
+
 
 @dataclass(frozen=True, slots=True)
 class PreviewLabelResolution:
@@ -95,7 +97,7 @@ def format_preview_value(
     value: object, detail: PreviewValueDetail = PreviewValueDetail.COMPACT
 ) -> str | None:
     """Project display values by nominal type, without knowing config field names."""
-    if callable(value) and not isinstance(value, type):
+    if callable(value):
         return type(value).__name__
     return str(value)
 
@@ -110,6 +112,12 @@ def _format_enum(value: Enum, detail=PreviewValueDetail.COMPACT) -> str | None:
     return value.name if value.value is not None else None
 
 
+@format_preview_value.register(type)
+def _format_type(value: type, detail=PreviewValueDetail.COMPACT) -> str:
+    declaration = canonical_declaration_mro(value)[0]
+    return FieldDisplayText.from_field_name(declaration.__name__).display_name
+
+
 @format_preview_value.register(FunctionType)
 @format_preview_value.register(MethodType)
 def _format_function(value, detail=PreviewValueDetail.COMPACT) -> str:

tests/test_preview_value_names.py

@@ -0,0 +1,55 @@
+"""Class-valued choices have readable captions without changing their identity."""
+
+from abc import ABCMeta
+from dataclasses import dataclass
+
+import pytest
+from objectstate.lazy_factory import LazyDataclassFactory
+
+from formbridge.forms.ui_utils import FieldDisplayText
+from formbridge.managers.preview_formatting import ManagerPreviewFieldFormatter
+from formbridge.utils.preview_formatters import PreviewFieldFormatRequest, format_preview_value
+
+
+@pytest.mark.parametrize(
+    ("name", "expected"),
+    [
+        ("read_previous_step", "Read Previous Step"),
+        ("ReadPreviousStep", "Read Previous Step"),
+        ("SourceVoxelSpacing", "Source Voxel Spacing"),
+        ("HTTPServer", "HTTP Server"),
+        ("Channel", "Channel"),
+    ],
+)
+def test_display_text_owns_parameter_and_class_name_spacing(name: str, expected: str) -> None:
+    text = FieldDisplayText.from_field_name(name)
+    assert text.display_name == expected
+    assert text.field_label == f"{expected}:"
+    assert text.checkbox_label == f"Enable {expected}"
+    assert text.group_title == expected
+
+
+@pytest.mark.parametrize("metaclass", [type, ABCMeta])
+def test_class_valued_choice_uses_shared_preview_formatter(metaclass: type) -> None:
+    choice = metaclass("ReadPreviousStep", (), {"name": "previous"})
+    assert format_preview_value(choice) == "Read Previous Step"
+    request = PreviewFieldFormatRequest("processing.input_source", choice, object)
+    assert ManagerPreviewFieldFormatter().format_field(request) == "input_source:Read Previous Step"
+    assert request.value is choice
+    assert choice.name == "previous"
+
+
+def test_lazy_class_caption_uses_the_original_declaration() -> None:
+    @dataclass
+    class SourceVoxelSpacing:
+        value: int = 1
+
+    lazy = LazyDataclassFactory.make_lazy_simple(SourceVoxelSpacing, "LazyCaptionSpacing")
+    assert format_preview_value(lazy) == "Source Voxel Spacing"
+
+
+def test_callable_preview_keeps_function_name() -> None:
+    def read_previous_step() -> None:
+        pass
+
+    assert format_preview_value(read_previous_step) == "read_previous_step"