PHP: Looping over an object loops over member array - php

Question

foreach ($pElements as $pElement) {
var_dump($pElement);
}
If I execute the above, I notice it dumps each value in the 'nodes' array even though $pElement is an object. Can anyone explain this behavior?
At first I thought running foreach on an object automatically searches for a member array, but the first listed array namespaces seems to be ignored.
Here is the full object $pElements:
/var/www/html/phpTestArea/index.php:35:
object(Symfony\Component\DomCrawler\Crawler)[38]
protected 'uri' => null
private 'defaultNamespacePrefix' => string 'default' (length=7)
private 'namespaces' =>
array (size=0)
empty
private 'baseHref' => null
private 'document' =>
object(DOMDocument)[2]
public 'doctype' => string '(object value omitted)' (length=22)
public 'implementation' => string '(object value omitted)' (length=22)
<public properties removed>
private 'nodes' =>
array (size=2)
0 =>
object(DOMElement)[36]
<public properties removed>
1 =>
object(DOMElement)[35]
<public properties removed>
private 'isHtml' => boolean true

Answer 1

If you take a look at the source code of that class here, you can see that it implements two interfaces, defined as follow:
Countable: this define how the instances of the class should behave when passed to the native php count function. The counting depends on the implementation.
interface Countable {
abstract public count(void): int
}
IteratorAggregate: this is the one that return an iterator (which extends Traversable) that defines how and what should be traversed.
interface IteratorAggregate extends Traversable {
abstract public getIterator(void): Traversable
}
So if you look closely into the source code for these two functions, you will see how these are implemented:
/**
* #return int
*/
public function count()
{
return \count($this->nodes);
}
/**
* #return \ArrayIterator|\DOMElement[]
*/
public function getIterator()
{
return new \ArrayIterator($this->nodes);
}
So if you call count($pElements), the object's internal count function will be executed, therefore you would get the count of the nodes property.
In the same way, if you iterate with a foreach over $pElements, you are iterating over the nodes property, as this is the behaviour defined by getIterator().