lazy-listeners.md

Lazy Listeners

To save on the cost of loading potentially expensive objects, you may want to lazy load listeners. For the purposes of this library, lazy loading refers specifically to retrieving a listener from a PSR-11 dependency injection container at the point of listener invocation.

The library provides Phly\EventDispatcher\LazyListener to facilitate such operations. The class has a constructor that accepts a PSR-11 container, the string service name to pull from the container, and, optionally, a method to call on that service (if none is provided, it assumes the class is invokable).

As an example:

$listener = new LazyListener($container, ActualListener::class);

lazyListener()

As a shortcut, we also provide the function Phly\EventDispatcher\lazyListener(), which accepts the same arguments as the LazyListener constructor. This is particularly useful when attaching listeners:

use function Phly\EventManager\lazyListener;

$provider->listen(lazyListener($container, ActualListener::class));