Using Rails 3 and Haml 3, how do I configure Haml?

Question

I'm using Rails 3.0.0.beta3 and Haml 3.0.0.rc.2, and I can't find where I need to place the configuration lines for Haml (nor what they are in the new version, for that matter). Using Rails 2.3.5 and Haml 2, I would do

Haml::Template.options[:format] = :html5

in environment.rb. Or, in Sinatra,

set :haml, {:format => :html5}

in my main file. But in Rails 3 everything's been changed around, and no matter where I put that configuration line, I get an undefined method or undefined object error.

Answer 1

In accordance with Rails 3's lazy-loading philosophy, Haml only initializes itself once ActionView::Base is loaded, which may not have happened when the configuration file is being parsed. In order to run code once Haml's been loaded, you need to run it in a ActiveSupport#on_load block. For example:

ActiveSupport.on_load(:action_vew) do
  Haml::Template.options[:format] = :html5
end

I'm considering ways of making the configuration accessible before the full Haml system has been loaded, either by defining Haml::Template.options earlier or adding a special config.haml hash.