#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2021, 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__)
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# Imports
#-----------------------------------------------------------------------------
# Standard library imports
from inspect import signature
from typing import (
TYPE_CHECKING,
Any,
Callable,
Dict,
List,
Sequence,
Type,
Union,
cast,
)
# Bokeh imports
from ..core.types import Unknown
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
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# 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 receving the event as the param, even if that
# means auto-magically wrapping user-supplied callbacks for awhile.
EventCallbackWithEvent = Callable[[Event], None]
EventCallbackWithoutEvent = Callable[[], None]
EventCallback = Union[EventCallbackWithEvent, EventCallbackWithoutEvent]
PropertyCallback = Callable[[str, Unknown, Unknown], 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: List[str]
_event_callbacks: Dict[str, List[EventCallback]]
def __init__(self, *args: Any, **kw: Any) -> None:
super().__init__(*args, **kw) # type: ignore[call-arg] # https://github.com/python/mypy/issues/5887
self._event_callbacks = {}
[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')
if event not in self._event_callbacks:
self._event_callbacks[event] = [cb for cb in callbacks]
else:
self._event_callbacks[event].extend(callbacks)
if event not in self.subscribed_events:
self.subscribed_events.append(event)
def _trigger_event(self, event: ModelEvent) -> None:
def invoke() -> None:
for callback in self._event_callbacks.get(event.event_name,[]):
if event._model_id 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) # type: ignore[call-arg] # https://github.com/python/mypy/issues/5887
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: Unknown, new: Unknown,
hint: DocumentPatchedEvent | None = None, setter: Setter | None = None) -> None:
''' Trigger callbacks for ``attr`` on this object.
Args:
attr (str) :
old (object) :
new (object) :
Returns:
None
'''
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
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#-----------------------------------------------------------------------------
# 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)
formatted_args = str(sig)
error_msg = what + " must have signature func(%s), got func%s"
all_names, default_values = get_param_info(sig)
nargs = len(all_names) - len(default_values)
if nargs != len(fargs):
raise ValueError(error_msg % (", ".join(fargs), formatted_args))
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# Code
#-----------------------------------------------------------------------------