克隆一个实例并链接一个方法调用，可能吗？

Is possible to clone an instance calling a method on it with chaining? This gives me a syntax error:

/**
 * Parse an object containing (eventually) "duration" property or "year" (and
 * eventually) "month" properties.
 *
 * @return array Array containing start date and end date DateTime objects.
 */
public function parseTimeArgs($args)
{
    $now = new DateTime();

    if(isset($args->duration) && $duration = new DateInterval($args->duration))
        return array((clone $now)->sub($duration), $now);
}

No, this is not possible. You could use a "factory" method instead:

public function parseTimeArgs($args)
{
    $now = new DateTime();

    if(isset($args->duration) && $duration = new DateInterval($args->duration))
        return array($this->clone($now)->sub($duration), $now);
}

public function clone($object)
{
    return clone $object;
}

Side note: Using the new operator is currently not possible this way either. In the upcoming PHP 5.4 release this will be possible for new as follows:

$a = (new a())->doStuff()->foMoreStuff();

Clone however is not supported here.

public function parseTimeArgs($args)
{
    $now = new DateTime();
    $nowClone = clone $now;

    if(isset($args->duration) && $duration = new DateInterval($args->duration))
        return array($nowClone->sub($duration), $now);
}