''' Provides ``PropertyCallbackManager`` and ``EventCallbackManager``
mixin classes for adding ``on_change`` and ``on_event`` callback
interfaces to classes.
'''
from __future__ import absolute_import
from six import string_types
from ..events import Event
from ..util.future import get_param_info, format_signature, signature
def _check_callback(callback, fargs, what="Callback functions"):
'''Bokeh-internal function to check callback signature'''
sig = signature(callback)
formatted_args = format_signature(sig)
error_msg = what + " must have signature func(%s), got func%s"
all_names, default_values = get_param_info(sig)
if len(all_names) - len(default_values) != len(fargs):
raise ValueError(error_msg % (", ".join(fargs), formatted_args))
[docs]class EventCallbackManager(object):
''' A mixin class to provide an interface for registering and
triggering event callbacks on the Python side.
'''
def __init__(self, *args, **kw):
super(EventCallbackManager, self).__init__(*args, **kw)
self._event_callbacks = dict()
def on_event(self, event, *callbacks):
if not isinstance(event, string_types) and issubclass(event, Event):
event = event.event_name
for callback in callbacks:
_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):
for callback in self._event_callbacks.get(event.event_name,[]):
if event._model_id is not None and self.id == event._model_id:
callback(event)
def _update_event_callbacks(self):
if self.document is None:
return
for key in self._event_callbacks:
self.document._subscribed_models[key].add(self)
[docs]class PropertyCallbackManager(object):
''' A mixin class to provide an interface for registering and
triggering callbacks.
'''
def __init__(self, *args, **kw):
super(PropertyCallbackManager, self).__init__(*args, **kw)
self._callbacks = dict()
[docs] def on_change(self, attr, *callbacks):
''' 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, *callbacks):
''' 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, old, new, hint=None, setter=None):
''' Trigger callbacks for ``attr`` on this object.
Args:
attr (str) :
old (object) :
new (object) :
Returns:
None
'''
def invoke():
callbacks = self._callbacks.get(attr)
if callbacks:
for callback in callbacks:
callback(attr, old, new)
if hasattr(self, '_document') and self._document is not None:
self._document._notify_change(self, attr, old, new, hint, setter, invoke)
else:
invoke()
