Haml in Rails Engine

I am developing Rails engine that uses HAML for views templates. So my gemspec has following: line

  s.add_runtime_dependency 'haml', ">= 3.0.18"

But when I use this gem in an application that does not use HAMl itself, HAML does not seem to 开发者_StackOverflow社区be initialized (though Gemfile.lock clearly states that it is in dependencies).

Should I add some HAML initialization in the engine code ?

I faced same issue. Fixed by requiring haml in engine.rb

require 'haml'

I think you can declare a standard gem dependency by putting your own gem requirement in the init.rb for your engine:

Rails::Initializer.run do |config|
  config.gem 'haml', :version => 'haml'    
end