EVENT: Usability on handler's event argument

[pauleveritt]

Some suggestions...

Optional?

The handler is currently defined with event=None. Looking at MDN, I don't believe None should be allowed. It appears the decorator has no real effect if event is None.

event -> trigger

Calling it event is going to make it seem like an instance of Event. HTMX uses htmx-trigger="click". Perhaps we could use trigger.

Positional vs. Keyword

I suggest the first argument (event type) is positional, everything else is keyword. The current zen of Python might be moving towards all-keyword.

Tooling-friendly contraint on event type

It sucks when you slightly misspell an event name. On the HTML/JS side, tools will warn you. Would be nice on the Python side.

We could do an Enum. I think Brett Cannon did a Twitter poll, not sure if people liked that.

We could instead do it on the type hinting side, with a union of Literal for each possible value. But perhaps we don't want this at all, for the (very rare) case of custom events.