Faking method attributes in PHP?

This is how I ended up solving this. The article provided by Kevin was a huge help. By using ReflectionClass and ReflectionMethod::getDocComment, I can walk through the phpDoc comments very easily. A small regular expression finds any @route, and is registered to the method.

Reflection is not that quick (in our case, about 2,5 times as slow as having hard-coded calls to RegiserRoute in a separate function), and since we have a lot of routes, we had to cache the finished list of routes in Memcached, so reflection is unnecessary on every page load. In total we ended up going from taking 7ms to register the routes to 1,7ms on average when cached (reflection on every page load used 18ms on average.

The code to do this, which can be overridden in a subclass if you need manual registration, is as follows:

public static function RegisterRoutes()
{
    $sClass = get_called_class(); // unavailable in PHP < 5.3.0
    $rflClass = new ReflectionClass($sClass);
    foreach ($rflClass->getMethods() as $rflMethod)
    {
        $sComment = $rflMethod->getDocComment();
        if (preg_match_all('%^\s*\*\s*@route\s+(?P<route>/?(?:[a-z0-9]+/?)+)\s*$%im', $sComment, $result, PREG_PATTERN_ORDER)) 
        {
            foreach ($result[1] as $sRoute)
            {
                $sMethod = $rflMethod->GetName();
                $oRouteManager->RegisterRoute($sRoute, array($sClass, $sMethod));
            }
        }
    }
}

Thanks to everyone for pointing me in the right direction, there were lots of good suggestions here! We went with this approach simply because it allows us to keep the route close to the code it invokes:

class CSomeRoutable extends CRoutable
{
    /**
     * @route /foo/bar
     * @route /for/baz
     */
    public static function SomeRoute($SomeUnsafeParameter)
    {
        // this is accessible through two different routes
        echo (int)$SomeUnsafeParameter;
    }
}

Using PHP 5.3, you could use closures or "Anonymous functions" to tie the code to the route.

For example:

<?php
class Router
{
    protected $routes;
    public function __construct(){
        $this->routes = array();
    }

    public function RegisterRoute($route, $callback) {
       $this->routes[$route] = $callback;
    }

    public function CallRoute($route)
    {
        if(array_key_exists($route, $this->routes)) {
            $this->routes[$route]();
        }
    }
}


$router = new Router();

$router->RegisterRoute('admin/test/', function() {
    echo "Somebody called the Admin Test thingie!";
});

$router->CallRoute('admin/test/');
// Outputs: Somebody called the Admin Test thingie!
?>

Here's a method which may suit your needs. Each class that contains routes must implement an interface and then later loop through all defined classes which implement that interface to collect a list of routes. The interface contains a single method which expects an array of UrlRoute objects to be returned. These are then registered using your existing URL routing class.

Edit: I was just thinking, the UrlRoute class should probably also contain a field for ClassName. Then $oRouteManager->RegisterRoute($urlRoute->route, array($className, $urlRoute->method)) could be simplified to $oRouteManager->RegisterRoute($urlRoute). However, this would require a change to your existing framework...

interface IUrlRoute
{
    public static function GetRoutes();
}

class UrlRoute
{
    var $route;
    var $method;

    public function __construct($route, $method)
    {
        $this->route = $route;
        $this->method = $method;
    }
}

class Page1 implements IUrlRoute
{
    public static function GetRoutes()
    {
        return array(
            new UrlRoute('page1/test/', 'test')
        );
    }

    public function test()
    {
    }
}

class Page2 implements IUrlRoute
{
    public static function GetRoutes()
    {
        return array(
            new UrlRoute('page2/someroute/', 'test3'),
            new UrlRoute('page2/anotherpage/', 'anotherpage')
        );
    }

    public function test3()
    {
    }

    public function anotherpage()
    {
    }
}

$classes = get_declared_classes();
foreach($classes as $className)
{
    $c = new ReflectionClass($className);
    if( $c->implementsInterface('IUrlRoute') )
    {
        $fnRoute = $c->getMethod('GetRoutes');
        $listRoutes = $fnRoute->invoke(null);

        foreach($listRoutes as $urlRoute)
        {
            $oRouteManager->RegisterRoute($urlRoute->route, array($className, $urlRoute->method));  
        }
    }
}