Behavior of Various Ways to Loop over a PHP Object with Private/Protected Properties

object-loops.php

<?php

class A {
	protected $protected = 'protected';
	private $private = 'private';
	public $public = 'public';

	function loop_array() {
		foreach ( (array) $this as $key => $value ) {
			var_export( "$key => $value" );
			echo "\n";
		}
	}

	function loop_object() {
		foreach ( $this as $key => $value ) {
			var_export( "$key => $value" );
			echo "\n";
		}
	}

	function loop_object_vars() {
		foreach ( get_object_vars( $this ) as $key => $value ) {
			var_export( "$key => $value" );
			echo "\n";
		}
	}
}

$a = new A;

echo "External Array Loop\n";

foreach ( (array) $a as $key => $value ) {
	var_export( "$key => $value" );
	echo "\n";
}

echo "\n";

echo "External Object Loop\n";

foreach ( $a as $key => $value ) {
	var_export( "$key => $value" );
	echo "\n";
}

echo "\n";

echo "External Object_Vars Loop\n";

foreach ( get_object_vars( $a ) as $key => $value ) {
	var_export( "$key => $value" );
	echo "\n";
}

echo "\n";

echo "Internal Array Loop\n";

$a->loop_array();

echo "\n";

echo "Internal Object Loop\n";

$a->loop_object();

echo "\n";

echo "Internal Object_Vars Loop\n";

$a->loop_object_vars();