Sep 2nd, 2013

How heavy is Silex?

Quite often silex has been described as heavy or bloated. It's time to put this myth to rest.

symfony component cookie monster


Silex: The world's largest microframework.

Silex: All the bloat of Symfony but with only half the features.

Silex is so big: It has more lines of code than your project.


What an excellent buzzword! Let's face it, this is an overloaded and mostly nebulous term.

I don't think it's possible to clearly define what it means. However, I want to give a definition of what it means in the context of silex. Silex is a route builder, a router, a DI container, based on Symfony2 components.

But the real answer lies in what silex doesn't do. Unlike a framework, silex does not provide any conventions. That means that you are forced to architect your own code base. It gives you a lot of power and responsibility.

So what does micro mean? Is it about lines of code? Amount of dependencies? No, it's not.

While I agree that less lines of code and less dependencies are desirable, that is not the top priority. Micro means that silex exposes a minimal interface. It makes a minimal amount of decisions for you. Everything else follows from that principle.


So first of all, how many dependencies does silex have? As of right now, 7.

Here they are, in all of their glory:

  • pimple/pimple
  • psr/log
  • symfony/debug
  • symfony/event-dispatcher
  • symfony/http-kernel
  • symfony/http-foundation
  • symfony/routing

Each one of them does one specific thing. Each is reasonably small in size.

Of course, silex could have implemented all of those features itself. But it would mean less re-use, less battle-tested libraries, less interoperability.

To put this into perspective, the Symfony2 standard edition installs 60 packages, 41 of which are symfony components. The ZF2 skeleton installs all of the 49 components. Laravel4 ships with 58 packages, 28 of which are laravel components.

The point of this exercise is not to bash other frameworks. It's just to show that I'm not lying when I say silex has an add-what-you-need philosophy.

Number of classes, lines of code

Even though keeping lines of code down is not the primary goal of silex, we made sure not to include code that is not needed. So what exactly do you get when you use silex?

I grabbed the fine code-measuring tool cloc ran some analysis. After removing tests, the entire code base (including deps) consists of 16831 NCLOC in 280 classes. The whole tree (including tests) amounts to 3.5 MiB.

However, during a standard request only a fraction of that code is actually loaded. The following 50 classes are actually used:

* Silex\Application
* Silex\Controller
* Silex\ControllerCollection
* Silex\ControllerResolver
* Silex\EventListener\ConverterListener
* Silex\EventListener\LocaleListener
* Silex\EventListener\MiddlewareListener
* Silex\EventListener\StringToResponseListener
* Silex\ExceptionHandler
* Silex\LazyUrlMatcher
* Silex\RedirectableUrlMatcher
* Silex\Route
* Symfony\Component\EventDispatcher\Event
* Symfony\Component\EventDispatcher\EventDispatcher
* Symfony\Component\EventDispatcher\EventDispatcherInterface
* Symfony\Component\EventDispatcher\EventSubscriberInterface
* Symfony\Component\HttpFoundation\FileBag
* Symfony\Component\HttpFoundation\HeaderBag
* Symfony\Component\HttpFoundation\ParameterBag
* Symfony\Component\HttpFoundation\Request
* Symfony\Component\HttpFoundation\Response
* Symfony\Component\HttpFoundation\ResponseHeaderBag
* Symfony\Component\HttpFoundation\ServerBag
* Symfony\Component\HttpKernel\Controller\ControllerResolver
* Symfony\Component\HttpKernel\Controller\ControllerResolverInterface
* Symfony\Component\HttpKernel\Event\FilterControllerEvent
* Symfony\Component\HttpKernel\Event\FilterResponseEvent
* Symfony\Component\HttpKernel\Event\GetResponseEvent
* Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent
* Symfony\Component\HttpKernel\Event\KernelEvent
* Symfony\Component\HttpKernel\Event\PostResponseEvent
* Symfony\Component\HttpKernel\EventListener\LocaleListener
* Symfony\Component\HttpKernel\EventListener\ResponseListener
* Symfony\Component\HttpKernel\EventListener\RouterListener
* Symfony\Component\HttpKernel\HttpKernel
* Symfony\Component\HttpKernel\HttpKernelInterface
* Symfony\Component\HttpKernel\KernelEvents
* Symfony\Component\HttpKernel\TerminableInterface
* Symfony\Component\Routing\CompiledRoute
* Symfony\Component\Routing\Matcher\RedirectableUrlMatcher
* Symfony\Component\Routing\Matcher\RedirectableUrlMatcherInterface
* Symfony\Component\Routing\Matcher\UrlMatcher
* Symfony\Component\Routing\Matcher\UrlMatcherInterface
* Symfony\Component\Routing\RequestContext
* Symfony\Component\Routing\RequestContextAwareInterface
* Symfony\Component\Routing\Route
* Symfony\Component\Routing\RouteCollection
* Symfony\Component\Routing\RouteCompiler
* Symfony\Component\Routing\RouteCompilerInterface

Those 50 classes have a total of 4018 NCLOC.

Is that more than something like slim, limonade or breeze? Yes. By a factor of 2-4. Does that matter? I don't think so.

It is still sufficiently small. I consider re-use, isolation and interop provided by silex better than in the other listed projects.

Minimal interface

For the most part you will only ever deal with the following types:

  • Silex\Application
  • Silex\Controller
  • Silex\Route
  • Symfony\Component\HttFoundation\Request
  • Symfony\Component\HttFoundation\Response
  • Pimple

Learn them, and you can effectively use silex.


  • Minimal interface > minimal lines of code.
  • Silex is quite lightweight.
  • The entire public API consists of 5 classes.
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