platypush/platypush/event/__init__.py

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import inspect
import logging
import threading
class EventGenerator(object):
"""
Abstract class for event generators. It allows to fire events to the bus and
trigger/register/unregister custom callback handlers associated to event
types. Both plugins and backends extend this class.
"""
2020-09-27 01:33:38 +02:00
logger = logging.getLogger('platypush')
def __init__(self, *args, **kwargs):
self._event_handlers = {} # Event type => callback map
def fire_event(self, event):
"""
Fires an event (instance of :class:`platypush.message.event.Event` or a
subclass) to the internal bus and triggers any handler callback
associated to the event type or any of its super-classes.
:param event: Event to fire
:type event: :class:`platypush.message.event.Event` or a subclass
"""
def hndl_thread():
hndl(event)
from platypush.backend import Backend
from platypush.context import get_bus
bus = self.bus if isinstance(self, Backend) else get_bus()
if not bus:
self.logger.warning('No bus available to post the event: {}'.format(event))
else:
bus.post(event)
handlers = set()
for cls in inspect.getmro(event.__class__):
if cls in self._event_handlers:
handlers.update(self._event_handlers[cls])
for hndl in handlers:
threading.Thread(target=hndl_thread).start()
def register_handler(self, event_type, callback):
"""
Registers a callback handler for a camera event type.
:param event_type: Event type to listen to. Must be a subclass of
:class:`platypush.message.event.Event`
:type event_type: :class:`platypush.message.event.Event` or a subclass
:param callback: Callback function. It will take an event of type
:class:`platypush.message.event.Event` as a parameter
:type callback: function
"""
if event_type not in self._event_handlers:
self._event_handlers[event_type] = set()
self._event_handlers[event_type].add(callback)
def unregister_handler(self, event_type, callback):
"""
Unregisters a callback handler from a camera event type.
:param event_type: Event type the callback is registered to
:type event_type: :class:`platypush.message.event.Event` or a subclass
:param callback: Callback function to unregister
:type callback: function
"""
if event_type not in self._event_handlers:
return
if callback not in self._event_handlers[event_type]:
return
self._event_handlers[event_type].remove(callback)
if not self._event_handlers[event_type]:
del self._event_handlers[event_type]
# vim:sw=4:ts=4:et: