Laravel - Get value instances via facades - laravel

Question

In Illuminate\Support\Facades\Facade abstract In method
protected static function resolveFacadeInstance($name)
{
if (is_object($name)) {
return $name;
}
if (isset(static::$resolvedInstance[$name])) {
return static::$resolvedInstance[$name];
}
return static::$resolvedInstance[$name] = static::$app[$name];
}
static::$app is an instance of Application. And static::$app[$name] that like access value of array, and i don't understand that, What technique here?
ex: static::$app['router'] it return instance of Router. Seem that get values of protected $instances in Illuminate\Container\Container
I think it like example ? but got FATAL ERROR Uncaught Error: Cannot use object of type Foo as array
class Foo
{
public $bar = 'barValue';
}
$foo = new Foo();
echo $foo['bar'];

Answer 1

If you check the API of Illuminate\Container\Container, you will notice that it implements ArrayAccess and consequently the following methods.
offsetExists()
offsetGet()
offsetSet()
offsetUnset()
ArrayAccess lets you access objects as arrays. Here's a very simplistic example of a Container.
<?php
class Container implements ArrayAccess {
private $items = array();
public function __construct() {
$this->items = [
'one' => 1,
'two' => 2,
'three' => 3,
];
}
public function offsetSet($offset, $value) {
if (is_null($offset)) {
$this->items[] = $value;
} else {
$this->items[$offset] = $value;
}
}
public function offsetExists($offset) {
return isset($this->items[$offset]);
}
public function offsetUnset($offset) {
unset($this->items[$offset]);
}
public function offsetGet($offset) {
return isset($this->items[$offset]) ? $this->items[$offset] : null;
}
}
$container = new Container();
echo $container['one']; // outputs 1
$container['four'] = 4; // adds 4 to $items.
echo $container['four']; // outputs 4
As you can see, you can access the Container object as an array since it implements ArrayAccess.
It also doesn't matter if the items property is not publicly accessible. In any case, the implementation of ArrayAccess means that it will allow us to retrieve those values as if they were in an array.