PHP Functions with "hooks" to add before, after, and around actions/fixers/filters/exception handlers/listeners/whatevers

mm.php

<?php
/**
 * MegaMethods
 * ===========
 *
 * They do stuff, on steroids
**/

namespace MM;

class Trampoline {
  private $hooks, $impl, $next;

	public function __construct(&$hooks, $impl) {
		$this->hooks =& $hooks;
		$this->impl = $impl;
		$this->next = count($hooks);
	}

	public function __invoke() {
		$args = func_get_args();
		if($this->next--) {
			$hook = $this->hooks[$this->next];
			$args[] = $this;
			return call_user_func_array($hook, $args);
		} else {
			return call_user_func_array($this->impl, $args);
		}
	}
}

class MegaMethod {
	private $impl, $hooks;

	public function __construct($impl) {
		$this->impl = $impl;
		$this->hooks = array();
	}

	public function __invoke() {
		$tramp = new Trampoline($this->hooks, $this->impl);
		return call_user_func_array($tramp, func_get_args());
	}

	public function add_hook($hookfn) {
		$this->hooks[] = $hookfn;
	}
}


$classify = new MegaMethod(function($num) {
	return (string) $num;
});

// optional, this is really handy for making the calls look more "normal" and eliminating "global $foo" all over
function classify($num) {
	global $classify;
	return $classify($num);
}

foreach(array(3 => "Fizz", 5 => "Buzz", 15 => "FizzBuzz") as $mod => $replace) {
	$classify->add_hook(function($num, $chain) use($mod, $replace) {
		return ($num % $mod) ? $chain($num) : $replace;
	});
}

foreach(range(1,15) as $num) {
	$class = classify($num);
	echo "$class\n";
}