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#!/usr/bin/env python # -*- coding: utf-8 -*-
############################################################################### # Copyright Kitware Inc. # # Licensed under the Apache License, Version 2.0 ( the "License" ); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. ###############################################################################
This module contains the Girder events framework. It maintains a global mapping of events to listeners, and contains utilities for callers to handle or trigger events identified by a name.
Listeners should bind to events by calling:
girder.events.bind('event.name', 'my.handler', handlerFunction)
And events should be fired in one of two ways; if the event should be handled synchronouly, fire it with:
girder.events.trigger('event.name', info)
And if the event should be handled asynchronously, use:
girder.events.daemon.trigger('event.name', info, callback)
For obvious reasons, the asynchronous method does not return a value to the caller. Instead, the caller may optionally pass the callback argument as a function to be called when the task is finished. That callback function will receive the Event object as its only argument. """
""" An Event object is created when an event is triggered. It is passed to each of the listeners of the event, which have a chance to add information to the event, and also optionally stop the event from being further propagated to other listeners, and also optionally instruct the caller that it should not execute its default behavior. """
# We might have a lot of events, so we use __slots__ to make them smaller 'info', 'name', 'propagate', 'defaultPrevented', 'responses', 'currentHandlerName' )
""" This can be used to instruct the triggerer of the event that the default behavior it would normally perform should not be performed. The semantics of this action are specific to the context of the event being handled, but a common use of this method is for a plugin to provide an alternate behavior that will replace the normal way the event is handled by the core system. """
""" Listeners should call this on the event they were passed in order to stop any other listeners to the event from being executed. """
""" Listeners that wish to return data back to the caller who triggered this event should call this to append their own response to the event.
:param response: The response value, which can be any type. """
""" This class is used to execute the pipeline for events asynchronously. This should not be invoked directly by callers; instead, they should use girder.events.daemon.trigger(). """
""" Loops over all queued events. If the queue is empty, this thread gets put to sleep until someone calls trigger() on it with a new event to dispatch. """
print TerminalColor.info('Stopped asynchronous event manager thread.')
""" Adds a new event on the queue to trigger asynchronously.
:param eventName: The event name to pass to the girder.events.trigger :param info: The info object to pass to girder.events.trigger """
""" Gracefully stops this thread. Will finish the currently processing event before stopping. """
""" Bind a listener (handler) to the event identified by eventName. It is convention that plugins will use their own name as the handlerName, so that the trigger() caller can see which plugin(s) responded to the event.
:param eventName: The name that identifies the event. :type eventName: str :param handlerName: The name that identifies the handler calling bind(). :type handlerName: str :param handler: The function that will be called when the event is fired. It must accept a single argument, which is the Event that was created by trigger(). This function should not return a value; any data that it needs to pass back to the triggerer should be passed via the addResponse() method of the Event. :type handler: function """ global _mapping
""" Removes the binding between the event and the given listener.
:param eventName: The name that identifies the event. :type eventName: str :param handlerName: The name that identifies the handler calling bind(). :type handlerName: str """ global _mapping
""" Clears the entire event map. Any bound listeners will be unbound. """ global _mapping
""" Fire an event with the given name. All listeners bound on that name will be called until they are exhausted or one of the handlers calls the stopPropagation() method on the event.
:param eventName: The name that identifies the event. :type eventName: str :param info: The info argument to pass to the handler function. The type of this argument is opaque, and can be anything. """ global _mapping
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