php52.php

<?php
include 'classes/markdown.php';

$parser = new Markdown();
//Transform text using parser.
echo $parser->transform($text);

php53.php

<?php

include 'classes/markdown.php';

class myMarkdown extends Markdown{
	public function __invoke($text) {
		return $this->transform($text);
	}
}


$parser = new myMarkdown();
echo $parser($text);

not really sure what the advantage is here... it is kind of neat though

You don't actually need to do this with the markdown parser, it is already part of the code.