drupal_rackish.php

<?php

class Kernel {
  function handle() {}
}

class DrupalApp {
  function __construct() {
    $this->kernel = new Kernel();
  }

  function call($request) {
    print "Generating response!\n";
    return $this->kernel->handle($request);
  }
}

class DrupalAppCache {
  function __construct($app) {
    $this->app = $app;
  }

  function call($request) {
    if ($cached_response = $this->isCached($request)) {
      print "Returning cached response!\n";
      return $cached_response;
    }
    else {
      print "Cache miss! Calling through!\n";
      $this->app->call($request);
    }
  }

  function isCached($request) {
    return FALSE;
  }
}

$apps = array();

if ($cache_enabled = TRUE) {
  $apps[] = 'DrupalAppCache';
}

$stack = array();
foreach ($apps as $app) {
  $stack[] = function ($next_app) use ($app) {
    return new $app($next_app);
  };
}

$request = array();
print array_reduce(array_reverse($stack), function ($a, $e) {
  $a = $a ?: new DrupalApp();
  return $e($a);
})->call($request);