sl: add Invoke function

libs/sl/sl.go

@@ -158,6 +158,24 @@ func Use[T any](l *ServiceLocator, slotKey slot[T]) (T, error) {
 	return v, nil
 }
 
+func Invoke[T any](l *ServiceLocator, slotKey slot[T]) error {
+
+	slot, ok := l.providers[slotKey]
+	if !ok {
+		return fmt.Errorf(`no injected value for type %s`, getTypeName[T]())
+	}
+
+	err := slot.checkInitialized(l)
+	if err != nil {
+		return err
+	}
+
+	v := slot.value.(T)
+
+	Logger.Printf(`[slot: %s] using slot with value of type %T`, getTypeName[T](), v)
+	return nil
+}
+
 // getTypeName is a trick to get the name of a type (even if it is an
 // interface type)
 func getTypeName[T any]() string {