2 years ago

If you want to reuse some code between multiple classes, using a trait is an alternative for extending the class. In that case the trait may be the better option because it doesn't become part of the type hierarchy, i.e. a class that uses a trait isn't "an instance of that trait".

This is the code for that trait, and if you ever attended one of my workshops, you'll know it already: trait EventRecording { /** * @var list */ private array $events = []; private function recordThat(object $event): void { $this->events[] = $event; } /** * @return list */ public function releaseEvents(): array { $events = $this->events; $this->events = []; return $events; }}

We could fix this issue by extracting the code into an object, (adding even more evidence to the statement that there's always an alternative for using a trait): final class EventRecording { /** * @var list */ private array $events = []; private function recordThat(object $event): void { //... } /** * @return list */ public function releaseEvents(): array { //... }}

We could again introduce a trait for that: trait ReleaseEvents { private EventRecording $eventRecording = new EventRecording(); /** * @return list */ public function releaseEvents(): array { return $this->eventRecording->releaseEvents(); }}