deep_hurting.rb

# Ended up overriding send.
# Seems a bit intense, but action-args are too awesome to not use.

class ActionController::Base
  
  class << self
    attr_accessor :action_argument_list
    alias_method :old_inherited, :inherited

    # Stores the argument lists for all methods for this class.
    #
    # ==== Parameters
    # klass<Class>::
    #   The controller that is being inherited from Merb::AbstractController.
    def inherited(klass)
      klass.action_argument_list = Hash.new do |h,k|
        args = klass.instance_method(k).get_args
        arguments = args[0]
        defaults = []
        arguments.each {|a| defaults << a[0] if a.size == 2} if arguments
        h[k] = [arguments || [], defaults]
      end
      old_inherited(klass)
    end
  end

  def send action, *args
    if action_methods.include?(action)
      arguments, defaults = self.class.action_argument_list[action]
      
      args = arguments.map do |arg, default|
        arg = arg
        p = params.key?(arg.to_sym)
        raise BadRequest unless p || (defaults && defaults.include?(arg))
        p ? params[arg.to_sym] : default
      end
    end
    super action, *args
  end
end

doesn't cut it.rb

#I tried this, but the spiral of deep hurting from the method no longer actually being the method killed me.
class ActionController::Base
  
  class << self
    attr_accessor :action_argument_list
    alias_method :old_inherited, :inherited

    # Stores the argument lists for all methods for this class.
    #
    # ==== Parameters
    # klass<Class>::
    #   The controller that is being inherited from Merb::AbstractController.
    def inherited(klass)
      klass.action_argument_list = Hash.new do |h,k|
        args = klass.instance_method(k).get_args
        arguments = args[0]
        defaults = []
        arguments.each {|a| defaults << a[0] if a.size == 2} if arguments
        h[k] = [arguments || [], defaults]
      end
      old_inherited(klass)
    end
  end

  # Calls an action and maps the params hash to the action parameters.
  #
  # ==== Parameters
  # action<Symbol>:: The action to call
  #
  # ==== Raises
  # BadRequest:: The params hash doesn't have a required parameter.
  def _call_action(action)
    arguments, defaults = self.class.action_argument_list[action]
    
    args = arguments.map do |arg, default|
      arg = arg
      p = params.key?(arg.to_sym)
      raise BadRequest unless p || (defaults && defaults.include?(arg))
      p ? params[arg.to_sym] : default
    end
    send(action, *args)
  end
  
  def perform_action
    if action_methods.include?(action_name)
      _call_action(action_name)
      default_render unless performed?
    elsif respond_to? :method_missing
      method_missing action_name
      default_render unless performed?
    else
      begin
        default_render
      rescue ActionView::MissingTemplate => e
        # Was the implicit template missing, or was it another template?
        if e.path == default_template_name
          raise UnknownAction, "No action responded to #{action_name}. Actions: #{action_methods.sort.to_sentence(:locale => :en)}", caller
        else
          raise e
        end
      end
    end
  end
end