Deprecate validate_properties_on_set=False

docs/source/properties.rst

@@ -205,7 +205,7 @@ Note that the constraints for functional properties are set by assigning a dicti
 .. note::
 
     Currently, property values are not validated when they are set directly in Python, only via HTTP.
-    Setting ``validate_properties_on_set = True`` in `~lt.Thing._class_settings` enables validation when they are set in Python. This may become default behaviour in the future.
+    Setting ``validate_properties_on_set = True`` in `~lt.Thing._class_settings` enables validation when they are set in Python. This will become default behaviour in the future.
 
 Property metadata
 -----------------

docs/source/public_api.rst

@@ -328,7 +328,7 @@ This page summarises the parts of the LabThings API that should be most frequent
         Whether properties should be validated against their model when set from Python.
         Properties are always validated when set over HTTP.
         By default, no validation is performed when they are set from Python.
-        Setting this key to `True` will enable validation: this is likely to become the default in the future.
+        Setting this key to `True` will enable validation: this will become the default in the future.
 
 
 .. py:class:: ThingConfig(/, **data: Any)

src/labthings_fastapi/thing_class_settings.py

@@ -89,17 +89,19 @@ def get_validate_properties_on_set(cls: "type[Thing]") -> bool:
     :return: whether validation should be performed.
     """
     settings = get_class_settings(cls)
-    if "validate_properties_on_set" not in settings:
+    value = settings.get(
+        "validate_properties_on_set",
+        False,
+    )
+    if not value:
         warnings.warn(
             DefaultWillChangeWarning(
                 "`get_validate_properties_on_set` will become `True` by default "
-                "in the future. Set this property explicitly to `True` or `False` in "
+                "in the future, and may become the only option. "
+                "Set this property to `True` in "
                 f"`{cls.__module__}.{cls.__name__}._class_settings` "
                 "to eliminate this warning."
             ),
             stacklevel=3,
         )
-    return settings.get(
-        "validate_properties_on_set",
-        False,
-    )
+    return value