A simple PHP timer class with interim marker support

timer.php

<?

/*
 * A simple PHP timer class with interim marker support
 *
 * Released with the karmaware tag - https://pete-rai.github.io/karmaware
 *
 * Website  : http://www.rai.org.uk
 * GitHub   : https://github.com/pete-rai
 * LinkedIn : https://uk.linkedin.com/in/raipete
 * NPM      : https://www.npmjs.com/~peterai
 *
 */

class Timer
{
    protected $start;
    protected $mark;

    public function __construct ()
    {
        $this->start = $this->mark = self::now ();
    }

    public static function now ()
    {
        return microtime (true);
    }

    public function mark ()
    {
        $now = self::now ();
        $tick = $now - $this->mark;
        $this->mark = $now;
        return $tick;
    }

    public function full ()
    {
        return self::now () - $this->start;
    }
}

/*

// --- test code only - leave commented out once working

$timer = new Timer ();

echo number_format ($timer->mark (), 6)."\n";
sleep (1);
echo number_format ($timer->mark (), 6)."\n";
sleep (2);
echo number_format ($timer->mark (), 6)."\n";
sleep (3);
echo number_format ($timer->mark (), 6)."\n";
sleep (5);
echo number_format ($timer->mark (), 6)."\n";
echo number_format ($timer->full (), 6)."\n";

*/