class_docstr: A base class for Bokeh properties with simple get/set and serialization
  behavior.
class_docstr_tok: ["A","base","class","for","Bokeh","properties","with","simple","get\/set","and","serialization","behavior","."]
docstr: Unconditionally send a change event notification for the property.
  
  Args:
      obj (HasProps)
          The object the property is being set on.
  
      old (obj) :
          The previous value of the property
  
      new (obj) :
          The new value of the property
  
      hint (event hint or None, optional)
          An optional update event hint, e.g. ``ColumnStreamedEvent``
          (default: None)
  
          Update event hints are usually used at times when better
          update performance can be obtained by special-casing in
          some way (e.g. streaming or patching column data sources)
  
      setter (ClientSession or ServerSession or None, optional) :
          This is used to prevent "boomerang" updates to Bokeh apps.
          (default: None)
  
          In the context of a Bokeh server application, incoming updates
          to properties will be annotated with the session that is
          doing the updating. This value is propagated through any
          subsequent change notifications that the update triggers.
          The session can compare the event setter to itself, and
          suppress any updates that originate from itself.
  
  
  Returns:
      None
code: def _trigger(
      self,
      obj: HasProps,
      old: Any,
      value: Any,
      *,
      hint: DocumentPatchedEvent | None = None,
      setter: Setter | None = None,
  ) -> None:
      """Unconditionally send a change event notification for the property.
  
      Args:
          obj (HasProps)
              The object the property is being set on.
  
          old (obj) :
              The previous value of the property
  
          new (obj) :
              The new value of the property
  
          hint (event hint or None, optional)
              An optional update event hint, e.g. ``ColumnStreamedEvent``
              (default: None)
  
              Update event hints are usually used at times when better
              update performance can be obtained by special-casing in
              some way (e.g. streaming or patching column data sources)
  
          setter (ClientSession or ServerSession or None, optional) :
              This is used to prevent "boomerang" updates to Bokeh apps.
              (default: None)
  
              In the context of a Bokeh server application, incoming updates
              to properties will be annotated with the session that is
              doing the updating. This value is propagated through any
              subsequent change notifications that the update triggers.
              The session can compare the event setter to itself, and
              suppress any updates that originate from itself.
  
  
      Returns:
          None
  
      """
      if hasattr(obj, "trigger"):
          obj.trigger(self.name, old, value, hint, setter)
  
imports: from __future__ import annotations
  import logging
  from copy import copy
  from types import FunctionType
  from typing import TYPE_CHECKING, Any, Callable, Generic, TypeVar
  from ...util.deprecation import deprecated
  from .singletons import Undefined
  from .wrappers import PropertyValueColumnData, PropertyValueContainer
label_desc: Use image node_id 21 for calling the PropertyDescriptor obj's underlying member method code with example usage: obj._trigger(obj, old, value) without return types