Registers the on_click function as a callback for click events.

Indicates that the on_click function will be invoked when a click event occurs.

When a user interacts with a UI element that generates a click event in a GUI or web framework.

Graphical user interfaces, web frontends, game loops, any event-driven system.

@event_handler(event='<event_name>') def <handler_name>(): pass

@event_handler(event='<event_name>') def <handler_name>(): pass

event_handler event_name handler_name

• click hover keypress scroll

• @click_handler @on_event

Omitting the event keyword argument Defining the handler with parameters when the decorator expects none Using parentheses incorrectly after @event_handler

@event_handler(event='hover') def on_hover(): pass @event_handler(event='keypress') def on_keypress(): pass @event_handler(event='submit') def on_submit(): return False

Confusing with framework-specific route decorators like @app.route in Flask Mixing up event names with DOM event types

• py-pt-cat-6-event-handler-event-hover-def-on_hover-pass
• py-pt-cat-6-event-handler-event-keypress-def_on_keypress-pass
• py-pt-cat-6-event-handler-event-scroll-def_on_scroll-pass

The decorator registers the function as a callback; the function body can be left empty with pass if logic resides elsewhere.

Signals to readers that the function is an event callback, setting expectations about when it will be invoked.

Think of attaching a listener to a button click.

async event handler with async def on_click(): await handle_click()