zen_garden.plugin_system.events¶

Event utilities for the plugin system.

Provides a base Event enum and an EventPublisher to register and trigger events.

Classes

`Event`(value[, names, module, qualname, ...])	Base enum for plugin events.
`EventPublisher`()	Class to register and trigger events.

class zen_garden.plugin_system.events.Event(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)¶

Base enum for plugin events.

Extend this class to declare specific events used by plugins.

Example

>>> class Event(Enum):
>>>     after_model_construction = auto()

The event definition can be used as a decorator as:

>>> @EventPublisher.register(Event.after_model_construction)
>>> def any_function(any_arg):
>>>     pass

The event can be triggered in the core as:

>>> EventPublisher.trigger(Event.after_model_construction, any_arg)

class zen_garden.plugin_system.events.EventPublisher¶

Class to register and trigger events.

Observers are callables that can be registered to a specific event. When an event is triggered, all registered observers are invoked in registration order with the provided arguments.

Example

An observer is defined in a plugin module as a function decorated with EventPublisher.register:

>>> @EventPublisher.register(Event.after_model_construction)
>>> def any_function(any_arg):
>>>     pass

classmethod deregister_all()¶: Deregister all observers for all events.

classmethod observers()¶: Returns all observers registered.

classmethod register(event: Event)¶

Decorator that registers a callable as an observer for event.

Parameters:: event (Event) – The event value to register the observer for.
Returns:: A decorator which takes a function and registers it.
Return type:: Callable

classmethod trigger(event: Event, *args, **kwargs)¶

Trigger event and call all registered observers.

Parameters:

event (Event) – The event to trigger.
*args – Positional arguments passed to observer callables.
**kwargs – Keyword arguments passed to observer callables.