a user class with dynamic 'has role' methods

role.rb

class Role
	include DataMapper::Resource
	has n, :users, :through => Resource
	property :id, Serial
	property :name, String
	property :short_name, String
	property :description, Text
	property :created_at, DateTime
	property :updated_at, DateTime
	default_scope(:default).update(:order => [:id]) # set default order
end

user.rb

class User
	include DataMapper::Resource
	has n, :roles, :through => Resource
	has 1, :userinfo
	property :id,     Serial
	property :login,  String
	property :full_time, Boolean, :default => true
	property :rate_mod, Integer, :default => 0
	property :created_at, DateTime
	property :updated_at, DateTime
	validates_is_unique :login

	# create on the fly the method to handle all the
	# is_a_superuser?
	def method_missing(method_id, *args)
		if match = matches_dynamic_role_check?(method_id)
			tokenize_roles(match.captures.first).each do |check|
				return true if roles.collect{|r| r.short_name }.include?(check)
			end
			return false
		else
			super
		end
	end

	private

	def matches_dynamic_role_check?(method_id)
		/^is_an?_([a-zA-Z]\w*)\?$/.match(method_id.to_s)
	end

	# might at some point add the _and_ token
	def tokenize_roles(string_to_split)
		string_to_split.split(/_or_/)
	end
end

user_controller.rb

class Users < Application
	# The basic authentication method
	before :ensure_authenticated
	# This used to make sure that the user is authorized to do anything in this controller
	# So take a look at the bottom for the authorization code it's very simple
	# because of the dynamic user method
	before :ensure_authorization

	def index
		#
	end

	def show(id)
		#
	end

	def new
		#
	end

	def edit(id)
		#
	end

	def create(user)
		#
	end

	def update(id, user, userinfo)
		#
	end

	def destroy(id)
		#
	end

	# only allow "user admins" or "super" users to use this controller
	def ensure_authorization
		throw(:halt, redirect("/race/home", :message => {:error => "You are not authorized to access that page." })) unless session.user.is_a_user_manager_or_super?
	end

end # Users