getIfSet.php

<?php
	class Helper {
		static function getIfSet(& $var) {
			if (isset($var)) {
				return $var;
			}
			return null;
		}
	}

	// Test Values
	$testValues = array(
		'foo1' => '123',
		'foo2' => '123',
	);
	
	$newArray = array(
		'foo1' => Helper::getIfSet($testValues['foo1']),
		'foo2' => Helper::getIfSet($testValues['foo2']),
		'foo3' => Helper::getIfSet($testValues['foo3']),
	);
	
	print_r($newArray);
	
?>

Really don't need a class here, it's just a function.