examples: improve the sendbus example (#13604)

examples/eventbus/eventbus.v

@@ -2,12 +2,32 @@ module main
 
 import some_module
 
-fn main() {
+struct Receiver {
-	mut sub := some_module.get_subscriber()
+mut:
-	sub.subscribe('error', on_error)
+	ok bool
-	some_module.do_work()
 }
 
-fn on_error(sender voidptr, e &some_module.MyError, x voidptr) {
+fn main() {
-	println(e.message)
+	mut sub := some_module.get_subscriber()
+	r := Receiver{}
+	sub.subscribe_method('event_foo', on_foo, r)
+	sub.subscribe('event_bar', on_bar)
+	sub.subscribe('event_baz', on_baz)
+
+	println('Receiver ok: ' + r.ok.str())
+	some_module.do_work()
+	println('Receiver ok: ' + r.ok.str())
+}
+
+fn on_foo(mut receiver Receiver, e &some_module.EventMetadata, sender voidptr) {
+	receiver.ok = true
+	println('on_foo :: ' + e.message)
+}
+
+fn on_bar(receiver voidptr, e &some_module.EventMetadata, sender voidptr) {
+	println('on_bar :: ' + e.message)
+}
+
+fn on_baz(receiver voidptr, event voidptr, d &some_module.Duration) {
+	println('on_baz :: ' + d.hours.str())
 }

examples/eventbus/modules/some_module/some_module.v

@@ -6,27 +6,27 @@ const (
 	eb = eventbus.new()
 )
 
-pub struct Work {
+pub struct Duration {
 pub:
 	hours int
 }
 
-pub struct MyError {
+pub struct EventMetadata {
 pub:
 	message string
 }
 
 pub fn do_work() {
-	work := Work{20}
+	duration := Duration{10}
-	for i in 0 .. 20 {
+	for i in 0 .. 10 {
 		println('working...')
-		if i == 15 {
+		if i == 5 {
-			error := &MyError{'There was an error.'}
+			event_metadata := &EventMetadata{'Iteration ' + i.str()}
-			some_module.eb.publish('error', work, error)
+			some_module.eb.publish('event_foo', duration, event_metadata)
-			some_module.eb.publish('error', work, error)
+			some_module.eb.publish('event_bar', duration, event_metadata)
-			return
 		}
 	}
+	some_module.eb.publish('event_baz', &Duration{42}, &EventMetadata{'Additional data at the end.'})
 }
 
 pub fn get_subscriber() eventbus.Subscriber {