Events

A tiny publish/subscribe event emitter: an EventBus is a dictionary mapping event names to a list of handler functions.

#include "abscom/abs.h"

Function	Description
var EventBus(void)	Create a bus (an ABS_DICT).
void on(var bus, const char *event_name, AbsFunc handler)	Register a handler for an event.
void emit(var bus, const char *event_name, var data)	Run every handler for the event, in registration order.

Handlers receive the emitted payload as their var argument and may return a value (ignored by emit). Calling emit for an event with no handlers is a no-op.

static int logins = 0;

static var on_user_login(var user) {
    logins++;
    print(v("Logged in:"), user);
    return None;
}

var bus = EventBus();
on(bus, "login", on_user_login);
on(bus, "login", on_user_login);

emit(bus, "login", v("Alice"));   /* runs on_user_login twice */
print(v("Logins:"), v(logins));   /* 2 */

See tests/test_events.c for the full test.