gistfile1.php

<?php

// One refactoring would be to gather most of this behavior in a Domain Event collection class.
// This could contain more of the behaviors we'd use in the trait. This is probably better and
// could encapsulate other behaviors like playheads neatly but it doesn't change the fact you
// still end up wanting a public method or a couple of protected helper functions duplicated.

// This is a simplified example, admittedly. Add in a couple extra properties or conditions and
// the desire for more leverage grows.

// At the same time, it also demonstrates how adding an abstraction (the DomainEventBuffer)
// inherently offers some additional leverage, though it doesn't completely solve the issue.

class DomainEventBuffer
{
    private $events = [];
    
    public function __construct($events = [])
    {
        $this->events = [];
    }

    public function raise($event)
    {
        $this->events[] = $event;
    }

    public function releaseAndResetEvents()
    {
        $pendingEvents = $this->events;
        $this->events = [];

        return new static($pendingEvents);
    }
}

class MyEntity
{
    private $eventBuffer;

    public function __construct()
    {
        // we could also do this lazily on a protected raise or release but that'd just
        // increase the boiler plate and thus the desire for a trait any more.
        $this->eventStream = new DomainEventBuffer();
    }
    
    public function releaseEvents() // still have to put this on every entity
    {
        return $this->eventBuffer->releaseAndResetEvents();
    }
}