Duncan Mac-Vicar P.

I was very happy that Rails Engines got merged in Rails 2.3. However I never liked that engines did not support overlaying static assets like they do with controllers, models and views. Even worse, the discussion was around “mirroring” the engine’s assets into the application public/ directory (like you can see in this railcast).

I imagined that doing something more transparent would be non-trivial. But I never asked myself why. When mentioning this limitation to Daniel when explaining how we use engines in our code, he asked the magical question: “Why?”.

I have been looking at Rails’s Rack support recently. I love Rack. And if you see how Rails builds its complex pieces over such simple components based on Rack, you realize how good Rack is for the Ruby community as a base component.

So, I tried the very first though: Create a Rake middleware called StaticOverlay that is initialized with various overlay directories. When the middleware is called it will look for the file in the overlays, and if it finds it in one, it will serve it (using Rack::File), if not, it just call the application (or next middleware in the chain).

Once I put the rack middleware together it worked out of the box, so I started a thread in rails core list to find out whether this would be a valid approach to hack a real patch and add support for this in Rails itself.

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  • Tags [rails, ruby, suse]
  • Categories [Software]