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# LazyListenerAggregate
`Laminas\EventManager\LazyListenerAggregate` exists to facilitate attaching a
number of listeners as lazy listeners.
## Usage
Similar to a [LazyListener](lazy-listener.md) or
[LazyEventListener](lazy-event-listener.md), the `LazyListenerAggregate` accepts
a definition (or, rather, set of definitions), a PSR-11 container instance, and
optionall an `$env` array to its constructor.
Unlike either, however, the definition provided is an array of definitions to
use to create `LazyEventListener` instances; you may also intersperse actual
`LazyEventListener` instances if desired.
As an example, let's assume we have two listeners,
`My\Application\RouteListener` and `My\Application\DispatchListener`; the first
will use its `onRoute()` method to listen to the `route` event at priority 100,
the second its `onDispatch()` method to listen to the `dispatch` event at
priority -100.
```php
use My\Application\DispatchListener;
use My\Application\RouteListener;
use Laminas\EventManager\LazyListenerAggregate;
$definitions = [
[
'listener' => RouteListener::class,
'method' => 'onRoute',
'event' => 'route',
'priority' => 100,
],
[
'listener' => DispatchListener::class,
'method' => 'onDispatch',
'event' => 'dispatch',
'priority' => -100,
],
];
$aggregate = new LazyListenerAggregate(
$definitions,
$container
);
$aggregate->attach($events);
```
Internally, the `LazyListenerAggregate` will create `LazyEventListener`
instances, and during its `attach()` phase use them to attach to the event
manager using the event and priority they compose.
Below is a functionally identical example, mixing in a concrete
`LazyEventListener` instance for one listener:
```php
use My\Application\DispatchListener;
use My\Application\RouteListener;
use Laminas\EventManager\LazyEventListener;
use Laminas\EventManager\LazyListenerAggregate;
$dispatchListener = new LazyEventListener([
'listener' => DispatchListener::class,
'method' => 'onDispatch',
'event' => 'dispatch',
'priority' => -100,
], $container);
$definitions = [
[
'listener' => RouteListener::class,
'method' => 'onRoute',
'event' => 'route',
'priority' => 100,
],
$dispatchListener,
];
$aggregate = new LazyListenerAggregate(
$definitions,
$container
);
$aggregate->attach($events);
```
## Recommendations
We recommend using `LazyListenerAggregate` when you have listeners you will be
pulling from a Dependency Injection Container, but which may not execute on
every request; this will help minimize the number of objects pulled from the
DIC. As pulling instances from a DIC is often an expensive operation, this can
be a healthy performance optimization.
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