Returns integer difference between calls to a callback. Mainly for usage with memory_get_usage and memory_get_peak_usage

Diff.php

<?php

/**
 * Returns integer difference between calls to a callback
 * Mainly for usage with memory_get_usage and memory_get_peak_usage
 *
 * Usage:
 * $memDiff = new Diff(function() { return memory_get_usage(true); });
 * do_somethin_memory_intensive();
 * echo $memDiff;
 */
class Diff
{
    protected $previous;
    protected $current;
    protected $autoUpdate;

    public function __construct(\Closure $callback, $callNow = true, $autoUpdate = true)
    {
        $this->autoUpdate = (bool) $autoUpdate;
        $this->callback = $callback;
        if ($callNow) {
            $this->update();
        }
    }

    public function getCurrent()
    {
        return $this->current;
    }

    public function update()
    {
        $this->previous = $this->current;
        return $this->current = call_user_func($this->callback);
    }

    public function getDiff()
    {
        return $this->current - $this->previous;
    }

    public function __toString()
    {
        if ($this->autoUpdate) {
            $this->update();
        }
        $diff = $this->getDiff();
        return ($diff > 0 ? '+' : '') . $diff;
    }
}