Add support for property overrides

src/bokeh/core/has_props.py

@@ -122,19 +122,28 @@ def is_DataModel(cls: type[HasProps]) -> bool:
     from ..model import DataModel
     return issubclass(cls, HasProps) and getattr(cls, "__data_model__", False) and cls != DataModel
 
+def _overridden_properties(class_dict: dict[str, Any]) -> dict[str, Any]:
+    overridden_properties: dict[str, Any] = {}
+    for name, prop in tuple(class_dict.items()):
+        if isinstance(prop, Override) and prop.property_overridden:
+            overridden_properties[name] = prop.property_
+    return overridden_properties
+
 def _overridden_defaults(class_dict: dict[str, Any]) -> dict[str, Any]:
     overridden_defaults: dict[str, Any] = {}
     for name, prop in tuple(class_dict.items()):
-        if isinstance(prop, Override):
+        if isinstance(prop, Override) and prop.default_overridden:
             del class_dict[name]
-            if prop.default_overridden:
-                overridden_defaults[name] = prop.default
+            overridden_defaults[name] = prop.default
     return overridden_defaults
 
-def _generators(class_dict: dict[str, Any]):
+def _generators(class_dict: dict[str, Any], overrides: dict[str, Any]):
     generators: dict[str, PropertyDescriptorFactory[Any]] = {}
     for name, generator in tuple(class_dict.items()):
-        if isinstance(generator, PropertyDescriptorFactory):
+        if name in overrides:
+            del class_dict[name]
+            generators[name] = overrides[name]
+        elif isinstance(generator, PropertyDescriptorFactory):
             del class_dict[name]
             generators[name] = generator
     return generators
@@ -184,15 +193,17 @@ class MetaHasProps(type):
     '''
 
     __properties__: dict[str, Property[Any]]
+    __overridden_properties__: dict[str, Property[Any]]
     __overridden_defaults__: dict[str, Any]
     __themed_values__: dict[str, Any]
 
     def __new__(cls, class_name: str, bases: tuple[type, ...], class_dict: dict[str, Any]):
         '''
 
         '''
+        overridden_properties = _overridden_properties(class_dict)
         overridden_defaults = _overridden_defaults(class_dict)
-        generators = _generators(class_dict)
+        generators = _generators(class_dict, overridden_properties)
 
         properties = {}
 
@@ -206,6 +217,7 @@ def __new__(cls, class_name: str, bases: tuple[type, ...], class_dict: dict[str,
                 properties[name] = descriptor.property
 
         class_dict["__properties__"] = properties
+        class_dict["__overridden_properties__"] = overridden_properties
         class_dict["__overridden_defaults__"] = overridden_defaults
 
         return super().__new__(cls, class_name, bases, class_dict)
@@ -220,15 +232,15 @@ def __init__(cls, class_name: str, bases: tuple[type, ...], _) -> None:
         for base in (x for x in bases if issubclass(x, HasProps)):
             base_properties.update(base.properties(_with_props=True))
         own_properties = {k: v for k, v in cls.__dict__.items() if isinstance(v, PropertyDescriptor)}
-        redeclared = own_properties.keys() & base_properties.keys()
+        redeclared = (own_properties.keys() - cls.__overridden_properties__.keys()) & base_properties.keys()
         if redeclared:
             warn(f"Properties {redeclared!r} in class {cls.__name__} were previously declared on a parent "
                  "class. It never makes sense to do this. Redundant properties should be deleted here, or on "
                  "the parent class. Override() can be used to change a default value of a base class property.",
                  RuntimeWarning)
 
         # Check for no-op Overrides
-        unused_overrides = cls.__overridden_defaults__.keys() - cls.properties(_with_props=True).keys()
+        unused_overrides = (cls.__overridden_properties__.keys() | cls.__overridden_defaults__.keys()) - cls.properties(_with_props=True).keys()
         if unused_overrides:
             warn(f"Overrides of {unused_overrides} in class {cls.__name__} does not override anything.", RuntimeWarning)
 

src/bokeh/core/property/override.py

@@ -26,7 +26,13 @@
 #-----------------------------------------------------------------------------
 
 # Standard library imports
-from typing import Generic, TypeVar
+from typing import TYPE_CHECKING, Generic, TypeVar
+
+# Bokeh imports
+from ...util.dataclasses import NotRequired, Unspecified
+
+if TYPE_CHECKING:
+    from .bases import Property
 
 #-----------------------------------------------------------------------------
 # Globals and constants
@@ -92,13 +98,22 @@ class Child(Parent):
 
     """
 
+    property_overridden: bool
+    property_: NotRequired[Property[T]]
+
     default_overridden: bool
-    default: T
+    default: NotRequired[T]
 
-    def __init__(self, *, default: T) -> None:
-        self.default_overridden = True
+    def __init__(self, property: NotRequired[Property[T]] = Unspecified, *, default: NotRequired[T] = Unspecified) -> None:
+        self.property_overridden = property is not Unspecified
+        self.property_ = property
+
+        self.default_overridden = default is not Unspecified
         self.default = default
 
+        if self.property_overridden and self.default_overridden:
+            raise ValueError("'property' and 'default' cannot be used simultaneously")
+
 #-----------------------------------------------------------------------------
 # Dev API
 #-----------------------------------------------------------------------------

src/bokeh/models/widgets/sliders.py

@@ -27,6 +27,7 @@
 # Bokeh imports
 from ...core.has_props import abstract
 from ...core.properties import (
+    Any,
     Bool,
     Datetime,
     Either,
@@ -96,6 +97,10 @@ def __init__(self, *args, **kwargs) -> None:
     # Initial or selected value, throttled according to report only on mouseup.
     # """)
 
+    value = Required(Any, help="""
+    Initial or selected value.
+    """)
+
     orientation = Enum("horizontal", "vertical", help="""
     Orient the slider either horizontally (default) or vertically.
     """)
@@ -135,6 +140,12 @@ class NumericalSlider(AbstractSlider):
     def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
 
+    step = Nullable(Positive(Float), default=1, help="""
+    The step between consecutive values for discrete sliders. If ``None``,
+    then the slider becomes a continuous slider and any value between
+    ``start`` and ``end`` can be picked.
+    """)
+
     format = Either(String, Instance(TickFormatter), help="""
     """)
 
@@ -149,14 +160,14 @@ class CategoricalSlider(AbstractSlider):
     def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
 
+    value = Override(Required(String, help="""
+    Initial or selected category.
+    """))
+
     categories = Required(Seq(String), help="""
     A collection of categories to choose from.
     """)
 
-    value = Required(String, help="""
-    Initial or selected value.
-    """)
-
     value_throttled = Readonly(Required(String), help="""
     Initial or throttled selected value.
     """)
@@ -176,20 +187,14 @@ def __init__(self, *args, **kwargs) -> None:
     The maximum allowable value.
     """)
 
-    value = Required(Float, help="""
-    Initial or selected value.
-    """)
+    value = Override(Required(Float, help="""
+    Initial or selected number.
+    """))
 
     value_throttled = Readonly(Required(Float), help="""
     Initial or selected value, throttled according to report only on mouseup.
     """)
 
-    step = Nullable(Positive(Float), default=1, help="""
-    The step between consecutive values for discrete sliders. If ``None``,
-    then the slider becomes a continuous slider and any value between
-    ``start`` and ``end`` can be picked.
-    """)
-
     format = Override(default="0[.]00")
 
 class RangeSlider(NumericalSlider):
@@ -199,9 +204,9 @@ class RangeSlider(NumericalSlider):
     def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
 
-    value = Required(Tuple(Float, Float), help="""
-    Initial or selected range.
-    """)
+    value = Override(Required(Tuple(Float, Float), help="""
+    Initial or selected range of numbers.
+    """))
 
     value_throttled = Readonly(Required(Tuple(Float, Float)), help="""
     Initial or selected value, only changed at the end of an interaction.
@@ -215,10 +220,6 @@ def __init__(self, *args, **kwargs) -> None:
     The maximum allowable value.
     """)
 
-    step = Float(default=1, help="""
-    The step between consecutive values.
-    """)
-
     format = Override(default="0[.]00")
 
 class MultiValuedSlider(NumericalSlider):
@@ -228,10 +229,9 @@ class MultiValuedSlider(NumericalSlider):
     def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
 
-    # TODO value = Override(Required(Seq(Float)), ...)
-    value = Required(Seq(Float), help="""
-    Initial or selected values.
-    """)
+    value = Override(Required(Seq(Float), help="""
+    Initial or selected numbers.
+    """))
 
     value_throttled = Readonly(Required(Seq(Float)), help="""
     Initial or selected values, only changed at the end of an interaction.
@@ -245,10 +245,6 @@ def __init__(self, *args, **kwargs) -> None:
     The maximum allowable value.
     """)
 
-    step = Float(default=1, help="""
-    The step between consecutive values.
-    """)
-
     format = Override(default="0[.]00")
 
 class DateSlider(NumericalSlider):
@@ -287,9 +283,9 @@ def value_as_date(self) -> date | None:
 
         return self.value
 
-    value = Required(Datetime, help="""
+    value = Override(Required(Datetime, help="""
     Initial or selected value.
-    """)
+    """))
 
     value_throttled = Readonly(Required(Datetime), help="""
     Initial or selected value, only changed at the end of an interaction.
@@ -303,10 +299,6 @@ def value_as_date(self) -> date | None:
     The maximum allowable value.
     """)
 
-    step = Int(default=1, help="""
-    The step between consecutive values, in units of days.
-    """)
-
     format = Override(default="%d %b %Y")
 
 class DateRangeSlider(NumericalSlider):
@@ -358,9 +350,9 @@ def value_as_date(self) -> tuple[date, date] | None:
             d2 = v2
         return d1, d2
 
-    value = Required(Tuple(Datetime, Datetime), help="""
-    Initial or selected range.
-    """)
+    value = Override(Required(Tuple(Datetime, Datetime), help="""
+    Initial or selected range of dates.
+    """))
 
     value_throttled = Readonly(Required(Tuple(Datetime, Datetime)), help="""
     Initial or selected value, only changed at the end of an interaction.
@@ -374,9 +366,9 @@ def value_as_date(self) -> tuple[date, date] | None:
     The maximum allowable value.
     """)
 
-    step = Int(default=1, help="""
+    step = Override(Int(default=1, help="""
     The step between consecutive values, in units of days.
-    """)
+    """))
 
     format = Override(default="%d %b %Y")
 
@@ -405,9 +397,9 @@ def value_as_datetime(self) -> tuple[datetime, datetime] | None:
             d2 = v2
         return d1, d2
 
-    value = Required(Tuple(Datetime, Datetime), help="""
-    Initial or selected range.
-    """)
+    value = Override(Required(Tuple(Datetime, Datetime), help="""
+    Initial or selected range of dates and times.
+    """))
 
     value_throttled = Readonly(Required(Tuple(Datetime, Datetime)), help="""
     Initial or selected value, only changed at the end of an interaction.
@@ -421,10 +413,10 @@ def value_as_datetime(self) -> tuple[datetime, datetime] | None:
     The maximum allowable value.
     """)
 
-    step = Int(default=3_600_000, help="""
+    step = Override(Int(default=3_600_000, help="""
     The step between consecutive values, in units of milliseconds.
     Default is one hour.
-    """)
+    """))
 
     # TODO step_unit = Enum("hour", ...)(default="hour")