Simple permissions

permit.rb

# A small example of Method Forwarding
#
# The permissions are stored on the object concerned with access control.
# You send a message to one object, which forwards it to the access controller.

class User
  attr_accessor :zombie
  def method_missing(meth, object, *args)
    if object.permissions
      object.send(meth, self, *args)
    else
      super
    end
  end
end

class Site
  attr_accessor :permissions
  class Permissions
    def allowed?(user)
      !user.zombie
    end

    def can_do_things?(user)
      false
    end
  end

  def initialize
    self.permissions = Permissions.new
  end

  def method_missing(meth, *args)
    options = args.last.is_a?(Hash) ? args.pop : {}
    object = args.shift
    permissions.send(meth, object, *args)
  rescue NoMethodError
    super
  end
end

site = Site.new
user = User.new
zombie = User.new
zombie.zombie = true

puts "user.can_do_things?(site)   #=> #{user.can_do_things?(site)}"
puts "zombie.can_do_things?(site) #=> #{zombie.can_do_things?(site)}"
puts "user.allowed?(site)         #=> #{user.allowed?(site)}"
puts "zombie.allowed?(site)       #=> #{zombie.allowed?(site)}"
puts "site.allowed?(user)         #=> #{site.allowed?(user)}"
puts "site.allowed?(zombie)       #=> #{site.allowed?(zombie)}"

puts "user.unknown_method?(site) #=> #{user.unknown_method?(site)}"