composer.json

{
    "require": {
        "silex/silex": "1.0.*@dev"
    },
    "autoload": {
        "psr-0": { "Igorw": "src" }
    }
}

FooController.php

<?php

// src/Igorw/FooController.php

namespace Igorw;

class FooController
{
    function getIndexAction()
    {
        return 'get index';
    }

    function getBarAction()
    {
        return 'get bar';
    }

    function postBarAction()
    {
        return 'post bar';
    }
}

index.php

<?php

// web/index.php

require 'vendor/autoload.php';

$app = new Silex\Application();

$app['debug'] = true;

$app->mount('/', new Igorw\ReflectionControllerProvider('Igorw\FooController'));

$app->run();

ReflectionControllerProvider.php

<?php

// src/Igorw/FooControllerProvider.php

namespace Igorw;

use Silex\Application;
use Silex\ControllerProviderInterface;

class ReflectionControllerProvider implements ControllerProviderInterface
{
    private $class;

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

    function connect(Application $app)
    {
        $controllers = $app['controllers_factory'];

        $reflection = new \ReflectionClass($this->class);
        $methods = $reflection->getMethods(\ReflectionMethod::IS_PUBLIC);

        foreach ($methods as $method) {
            $methodName = $method->getName();
            if (!preg_match('/^(get|post|put|delete|match)(.+)Action$/', $methodName, $matches)) {
                continue;
            }

            list($_, $httpMethod, $path) = $matches;
            $path = $this->adjustPath($path);

            $controllers->$httpMethod($path, $this->class.'::'.$methodName);
        }

        return $controllers;
    }

    private function adjustPath($path)
    {
        $path = lcfirst($path);
        $path = ('index' === $path) ? '' : $path;
        $path = '/'.$path;

        return $path;
    }
}