#-----------------------------------------------------------------------------
# Copyright (c) Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
#
# The full license is in the file LICENSE.txt, distributed with this software.
#-----------------------------------------------------------------------------
''' Provides ``PropertyCallbackManager`` and ``EventCallbackManager``
mixin classes for adding ``on_change`` and ``on_event`` callback
interfaces to classes.
'''
#-----------------------------------------------------------------------------
# Boilerplate
#-----------------------------------------------------------------------------
from __future__ import annotations
import logging # isort:skip
log = logging.getLogger(__name__)
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
# Standard library imports
from collections import defaultdict
from inspect import signature
from typing import (
TYPE_CHECKING,
Any,
Callable,
Sequence,
TypeAlias,
cast,
)
# Bokeh imports
from ..events import Event, ModelEvent
from ..util.functions import get_param_info
if TYPE_CHECKING:
from ..core.has_props import Setter
from ..core.types import ID
from ..document.document import Document
from ..document.events import DocumentPatchedEvent
#-----------------------------------------------------------------------------
# Globals and constants
#-----------------------------------------------------------------------------
__all__ = (
'EventCallbackManager',
'PropertyCallbackManager',
)
#-----------------------------------------------------------------------------
# General API
#-----------------------------------------------------------------------------
# TODO (bev) the situation with no-argument Button callbacks is a mess. We
# should migrate to all callbacks receiving the event as the param, even if that
# means auto-magically wrapping user-supplied callbacks for awhile.
EventCallbackWithEvent: TypeAlias = Callable[[Event], None]
EventCallbackWithoutEvent: TypeAlias = Callable[[], None]
EventCallback: TypeAlias = EventCallbackWithEvent | EventCallbackWithoutEvent
PropertyCallback: TypeAlias = Callable[[str, Any, Any], None]
[docs]
class EventCallbackManager:
''' A mixin class to provide an interface for registering and
triggering event callbacks on the Python side.
'''
document: Document | None
id: ID
subscribed_events: set[str]
_event_callbacks: dict[str, list[EventCallback]]
def __init__(self, *args: Any, **kw: Any) -> None:
super().__init__(*args, **kw)
self._event_callbacks = defaultdict(list)
[docs]
def on_event(self, event: str | type[Event], *callbacks: EventCallback) -> None:
''' Run callbacks when the specified event occurs on this Model
Not all Events are supported for all Models.
See specific Events in :ref:`bokeh.events` for more information on
which Models are able to trigger them.
'''
if not isinstance(event, str) and issubclass(event, Event):
event = event.event_name
for callback in callbacks:
if _nargs(callback) != 0:
_check_callback(callback, ('event',), what='Event callback')
self._event_callbacks[event].append(callback)
self.subscribed_events.add(event)
def _trigger_event(self, event: ModelEvent) -> None:
def invoke() -> None:
for callback in self._event_callbacks.get(event.event_name, []):
if event.model is not None and self.id == event.model.id:
if _nargs(callback) == 0:
cast(EventCallbackWithoutEvent, callback)()
else:
cast(EventCallbackWithEvent, callback)(event)
if self.document is not None:
from ..model import Model
self.document.callbacks.notify_event(cast(Model, self), event, invoke)
else:
invoke()
def _update_event_callbacks(self) -> None:
if self.document is None:
return
for key in self._event_callbacks:
from ..model import Model
self.document.callbacks.subscribe(key, cast(Model, self))
[docs]
class PropertyCallbackManager:
''' A mixin class to provide an interface for registering and
triggering callbacks.
'''
document: Document | None
_callbacks: dict[str, list[PropertyCallback]]
def __init__(self, *args: Any, **kw: Any) -> None:
super().__init__(*args, **kw)
self._callbacks = {}
[docs]
def on_change(self, attr: str, *callbacks: PropertyCallback) -> None:
''' Add a callback on this object to trigger when ``attr`` changes.
Args:
attr (str) : an attribute name on this object
callback (callable) : a callback function to register
Returns:
None
'''
if len(callbacks) == 0:
raise ValueError("on_change takes an attribute name and one or more callbacks, got only one parameter")
_callbacks = self._callbacks.setdefault(attr, [])
for callback in callbacks:
if callback in _callbacks:
continue
_check_callback(callback, ('attr', 'old', 'new'))
_callbacks.append(callback)
[docs]
def remove_on_change(self, attr: str, *callbacks: PropertyCallback) -> None:
''' Remove a callback from this object '''
if len(callbacks) == 0:
raise ValueError("remove_on_change takes an attribute name and one or more callbacks, got only one parameter")
_callbacks = self._callbacks.setdefault(attr, [])
for callback in callbacks:
_callbacks.remove(callback)
[docs]
def trigger(self, attr: str, old: Any, new: Any,
hint: DocumentPatchedEvent | None = None, setter: Setter | None = None) -> None:
''' Trigger callbacks for ``attr`` on this object.
'''
def invoke() -> None:
callbacks = self._callbacks.get(attr)
if callbacks:
for callback in callbacks:
callback(attr, old, new)
if self.document is not None:
from ..model import Model
self.document.callbacks.notify_change(cast(Model, self), attr, old, new, hint, setter, invoke)
else:
invoke()
#-----------------------------------------------------------------------------
# Dev API
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Private API
#-----------------------------------------------------------------------------
def _nargs(fn: Callable[..., Any]) -> int:
sig = signature(fn)
all_names, default_values = get_param_info(sig)
return len(all_names) - len(default_values)
def _check_callback(callback: Callable[..., Any], fargs: Sequence[str], what: str ="Callback functions") -> None:
'''Bokeh-internal function to check callback signature'''
sig = signature(callback)
all_names, default_values = get_param_info(sig)
nargs = len(all_names) - len(default_values)
if nargs != len(fargs):
expected = ", ".join(fargs)
received = str(sig)
raise ValueError(f"{what} must have signature func({expected}), got func{received}")
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
