Typed signatures for event handlers.

Signed-off-by: Pavel Patrin <ppatrin@nvidia.com>

events.go

@@ -90,16 +90,28 @@ func (em *events) Trigger(event Event) error {
 func (em *events) callTypedHandler(handler reflect.Value, args []any) error {
 	// Prepare slice of in arguments for handler.
 	handlerInArgs := make([]reflect.Value, 0, handler.Type().NumIn())
-	for index, eventArg := range args {
-		eventArgType := reflect.TypeOf(eventArg)
+
+	// Fill handler args with provided event args.
+	maxArgsLen := min(len(args), handler.Type().NumIn())
+	for index := 0; index < maxArgsLen; index++ {
+		eventArgType := reflect.TypeOf(args[index])
+		eventArgValue := reflect.ValueOf(args[index])
 		handlerArgType := handler.Type().In(index)
 		if !eventArgType.AssignableTo(handlerArgType) {
 			return fmt.Errorf(
 				"%w: type '%s' is not assignable to '%s' (index %d)",
 				HandlerArgTypeMismatchError, eventArgType, handlerArgType, index,
 			)
 		}
-		handlerInArgs = append(handlerInArgs, reflect.ValueOf(eventArg))
+		handlerInArgs = append(handlerInArgs, eventArgValue)
+	}
+
+	// Fill handler args with default type values.
+	if len(handlerInArgs) < handler.Type().NumIn() {
+		for index := len(handlerInArgs); index < handler.Type().NumIn(); index++ {
+			zeroValuePtr := reflect.New(handler.Type().In(index))
+			handlerInArgs = append(handlerInArgs, zeroValuePtr.Elem())
+		}
 	}
 
 	// Invoke original event handler function.

events_test.go

@@ -10,6 +10,8 @@ func TestEvents(t *testing.T) {
 	testEvent1Args := [][]any(nil)
 	testEvent2Args := [][]any(nil)
 	testEvent3Args := [][]any(nil)
+	testEvent4Args := [][]any(nil)
+	testEvent5Args := [][]any(nil)
 
 	ev := &events{events: make(map[string][]handler)}
 	ev.Subscribe("TestEvent1", func(args ...any) {
@@ -23,14 +25,26 @@ func TestEvents(t *testing.T) {
 		testEvent3Args = append(testEvent3Args, []any{x, y, z})
 		return nil
 	})
+	ev.Subscribe("TestEvent4", func(x string, y int) error {
+		testEvent4Args = append(testEvent4Args, []any{x, y})
+		return nil
+	})
+	ev.Subscribe("TestEvent5", func(x string, y int, z bool) error {
+		testEvent5Args = append(testEvent5Args, []any{x, y, z})
+		return nil
+	})
 
 	equal(t, ev.Trigger(NewEvent("TestEvent1", 1)), nil)
 	equal(t, ev.Trigger(NewEvent("TestEvent1", "x")), nil)
 	equal(t, ev.Trigger(NewEvent("TestEvent2", true)), nil)
 	equal(t, ev.Trigger(NewEvent("TestEvent3", "x", 1, true)), nil)
+	equal(t, ev.Trigger(NewEvent("TestEvent4", "x", 1, true)), nil)
+	equal(t, ev.Trigger(NewEvent("TestEvent5", "x", 1)), nil)
 	equal(t, testEvent1Args, [][]any{{1}, {"x"}})
 	equal(t, testEvent2Args, [][]any{{true}})
 	equal(t, testEvent3Args, [][]any{{"x", 1, true}})
+	equal(t, testEvent4Args, [][]any{{"x", 1}})
+	equal(t, testEvent5Args, [][]any{{"x", 1, false}})
 }
 
 func equal(t *testing.T, a, b any) {

go.mod

@@ -1,3 +1,3 @@
 module github.com/NVIDIA/gontainer
 
-go 1.20
+go 1.21