[HttpKernel] Missing documentation about HttpKernel Extension

[linaori]

Recently I've made a PR for the SecurityComponent to remove the SecurityContext in 3.0. I found something in the SecurityExtension that caught my eye:

$this->addClassesToCompile([
    // list of class names
]);

I've never seen this method before so I went on searching for it. It seems like the HttpKernel component has a custom Extension that adds this method and the SecurityExtension extends this. It seems like this makes it possible to add the contents of the classes to classes.php in your cache directory.

When I was looking for documentation, I couldn't find any. I was expecting it to be on at least one of the following pages:

• http://symfony.com/doc/current/cookbook/bundles/extension.html
• http://symfony.com/doc/current/components/http_kernel/introduction.html
• http://symfony.com/doc/current/book/performance.html

Should this be a feature that's documented? If that's the case, I can take a look at how it exactly works, implement it and write down when you should or should not add classes to this list.

[javiereguiluz]

👍 I agree that this feature should be documented in the articles you linked. Even if most developers won't need it, for complex applications it can improve the performance.

PS: by the way, this is one of the tips that I'll briefly explain in my SymfonyCon talk next week ;)

[linaori]

@javiereguiluz Ah that's very cool! Sadly I won't be there. If you want, you can update this issue with your slides (or what ever you are using), and I can try to incorporate the same subjects.

[wouterj]

@javiereguiluz talk can be found at: https://youtu.be/B8Sbo-JxKMo?t=7m11s

I propose to add a new section about adding classes to compile in cookbook/bundles/extension. We can then add a nice tip in book/performance linking to this new section. I won't add it to the HttpKernel components, as it's not talking about extensions at the moment (those component docs has to be extended).