translation_scope.rb

module ActionView
  module Helpers
    module TranslationHelper
      # Override translate method to consider translate_scope.
      def translate(key, options = {})
        I18n.translate(key, {:raise => I18n.raise_on_missing, :scope => (translate_scope.dup << options.delete(:add_scope)).compact}.merge(options))
      end
      alias :t :translate
      
      # Append scopes to the current translation scope.
      def with_translate_scope(*scopes)
        before = translate_scope.dup
        
        options = scopes.extract_options!
        if options[:absolute]
          @translate_scope = scopes
        else
          @translate_scope += scopes
        end
        
        yield
      ensure
        @translate_scope = before
      end

      # The current translation scope, default to the current controller name.
      def translate_scope
        @translate_scope ||= [(controller.controller_name rescue controller.mailer_name)]
      end
    end
  end
end

module MailerTranslationScope
  
private
  def t(*args)
    args << {:scope => self.class.name.underscore}.merge(args.extract_options!)
    I18n.translate(*args)
  end
end

module I18n
  class << self
    attr_accessor :raise_on_missing
  end
end

ActionMailer::Base.send(:include, MailerTranslationScope)