Add global event bus

[collindutter]

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Describe your changes

Added

• Global event bus, griptape.events.EventBus, for publishing and subscribing to events.

Changed

• BREAKING: Removed all uses of EventPublisherMixin in favor of EventBus.
• BREAKING: Removed EventPublisherMixin.

A couple things I'm unsure about:

1. Should this be a singleton or should we have a namespaced factory method similar to python's logging module? Something like:

def get_event_bus(namespace: str = DEFAULT_NAMESPACE) ...

I can't think of any scenario where you'd want multiple busses, especially since you can pass in many EventListeners.
2. If we stick with a singleton, does the PascalCase naming of the variable make sense? The idea was that it might convey the global nature of it, similar to how you might access static fields.

Issue ticket number and link

NA

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📚 Documentation preview 📚: https://griptape--1051.org.readthedocs.build//1051/

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[dylanholmes]

I really like the direction!

The changes look functionally good, but I'd like to chat before approving.

About the multiple buses scenario -- I can't really imagine a use case, would events get published to all of them or just some of them (if some of them, how would the publisher decide which)? If you just want to listen to a subset of events, the event listener should be able to filter out events it doesn't care about.

[collindutter]

@dylanholmes what do you think about dropping the event portion on all methods/fields in EventBus? EventBus.add_listener, for example.

[collindutter]

https://www.attrs.org/en/stable/init.html#private-attributes-and-aliases

[dylanholmes]

This is uglier than just not using attrs imo. Plus it still adds _event_listeners as an keyword arg in init.

I don't care that much though

[dylanholmes]

@dylanholmes what do you think about dropping the event portion on all methods/fields in EventBus? EventBus.add_listener, for example.

Not sure, I kind of like add_event_listener, but maybe I'm brainwashed by javascript in the browser. I don't really care either way honestly though. Another alternative could be EventBus.subscribe(...).

This seems like a good opportunity to mention another "syntax golfing" idea I had that I wasn't going to share publicly. Accept the EventListener init params directly in the method to avoid the boilerplate (...EventListener(...)...)

event_bus.add_event_listener(my_callback, event_types=[...])

[collindutter]

Not sure, I kind of like add_event_listener

Let's just leave it as is.

Accept the EventListener init params directly in the method to avoid the boilerplate

I like the conciseness, but I'd rather introduce even more breaking changes at this point. Let's evaluate in the future.

[dylanholmes]

Nice work!

Just one optional suggestion

[dylanholmes]

Does this need to be plural? Can there be a singular add_event_listener too?

[collindutter]

It does not _need_to be plural, no. Let's just leave it as is, docs will get an overhaul at some point soon.