A fix for missing functionality in php 5.2's DateTime class

datetime_52.class.php

<?php

/**
 * Provides backwards support for php 5.2's lack of setTimestamp and getTimestamp
 */
class DateTime_52 extends DateTime{
	/**
	 * Set the time of the datetime object by a unix timestamp
	 * @param int $unixtimestamp
	 * @return DateTime_52
	 */
	public function setTimestamp($unixtimestamp){
		if(!is_numeric($unixtimestamp) && !is_null($unixtimestamp)){
			trigger_error('DateTime::setTimestamp() expects parameter 1 to be long, '.gettype($unixtimestamp).' given', E_USER_WARNING);
		} else {
			$this->setDate(date('Y', $unixtimestamp), date('n', $unixtimestamp), date('d', $unixtimestamp));
			$this->setTime(date('G', $unixtimestamp), date('i', $unixtimestamp), date('s', $unixtimestamp));
		}
		return $this;
	}
	/**
	 * Get the time of the datetime object as a unix timestamp
	 * @return int a unix timestamp representing the time in the datetime object
	 */
	public function getTimestamp(){
		return $this->format('U');
	}
}

if(!function_exists('date_timestamp_get')){
	/**
	 * Get the timestamp of a DateTime object
	 * @param DateTime $object
	 * @see DateTime_52::getTimestamp
	 */
	function date_timestamp_get(DateTime &$object){
		return $object->getTimestamp();
	}

}


if(!function_exists('date_timestamp_set')){
	/**
	 * Set the timestamp of a DateTime object
	 * @param DateTime $object
	 * @param int $unixtimestamp
	 * @return DateTime_52
	 * @see DateTime_52::setTimestamp
	 */
	function date_timestamp_set(DateTime &$object, $unixtimestamp){
		return $object->setTimestamp($unixtimestamp);
	}

}

datetime_52Test.php

<?php
require_once 'PHPUnit/Framework.php';

require_once 'datetime52.class.php';

/**
 * Test class for DateTime_52.
 * Generated by PHPUnit on 2010-03-30 at 16:33:49.
 */
class DateTime_52Test extends PHPUnit_Framework_TestCase {
	/**
	 * @var DateTime_52
	 */
	protected $dt52;
	/**
	 * @var DateTime
	 */
	protected $dt;

	/**
	 * Sets up the fixture, for example, opens a network connection.
	 * This method is called before a test is executed.
	 */
	protected function setUp() {
		$this->dt52 = new DateTime_52;
		$this->dt = new DateTime;
	}

	/**
	 * Tears down the fixture, for example, closes a network connection.
	 * This method is called after a test is executed.
	 */
	protected function tearDown() {
	}

	public function testTimestamp() {
		$timestamps = array(
			0,
			Null,
			'12345',
			'-10',
		);
		foreach($timestamps as $value){
			$result52 = $this->dt52->setTimestamp($value);
			$result = $this->dt->setTimestamp($value);
			$this->assertEquals($result->getTimestamp(), $result52->getTimestamp());
		}
		$invalidTimestamps = array(
			array(),
			(object)array(),
			'asdf',
			PHP_EOL,
			1.2,
			PHP_INT_MAX,
		);
		foreach($invalidTimestamps as $value){
			try{
				$result52 = $this->dt52->setTimestamp($value);
				$this->fail('datetime did not throw an exception.');
			}catch(Exception $e){
				$message52 = $e->getMessage();
			}
			try{
				$result = $this->dt->setTimestamp($value);
				$this->fail('datetime did not throw an exception.');
			}catch(Exception $e){
				$message = $e->getMessage();
			}
			$this->assertEquals($message, $message52);
		}
	}
}
?>

Thanks for the code. I added the following to the setTime function to support different timezones.

public function setTimestamp($unixtimestamp){
    if(!is_numeric($unixtimestamp) && !is_null($unixtimestamp)){
        trigger_error('DateTime::setTimestamp() expects parameter 1 to be long, '.gettype($unixtimestamp).' given', E_USER_WARNING);
    } else {

        $sys_tz = date_default_timezone_get();
        date_default_timezone_set($this->getTimezone()->getName());

        $this->setDate(date('Y', $unixtimestamp), date('n', $unixtimestamp), date('d', $unixtimestamp));
        $this->setTime(date('G', $unixtimestamp), date('i', $unixtimestamp), date('s', $unixtimestamp));

        date_default_timezone_set($sys_tz);

    }
    return $this;
}