Padrino provides support to render templates dynamically (e.g. foo.js vs. foo.haml) based on request content type formats and also locales (e.g. en, fr, es).
If you're not making use of the locales, you can use that mechanism for other purposes with just a simple override. When you need to render dynamic templates across your application, this may be a better alternative than patching out Padrino's entire render method (it's quite long) or writing a separate rendering function that all actions would need to be aware of.
The example in the gist is for serving mobile-specific templates across a whole app. Should a request come in from an iphone, I'd like to serve foo.mobile.haml instead of foo.haml. I use rack-mobile-detect to set a header if a request was deemed mobile, and then I check that header by patching out Padrino::Rendering's locale method.
Note that you could use this simple override of the locale method to render dynamically based on most criteria you can think of.