Beginner Ruby Elevator Program

# ruby beginner elevator program
 
 
 # We might break this stuff up into more classes as the need to separate state and
 # behaviour of different entities emerges, for now we keep it simple and imagine
 # the state to be that of the building as a whole.
 #
 # new code added by calvin... work in progress, still figuring how to make it all work
 
 class Building
   GROUND_FLOOR = 0
   USER_FLOOR = gets.chomp # MM: You're using a constant here, did you mean to?

   attr_reader :elevator_on_floor
   attr_accessor :elevator_target_floor, :new_floor

   def initialize
     @elevator_on_floor = GROUND_FLOOR
     @elevator_target_floor = GROUND_FLOOR
     @new_floor = USER_FLOOR # MM: I'd look at passing this value into initialize instead
   end

   def call_elevator_to_floor( new_floor )
     # Check that the call floor is legal (in a real elevator you wouldn't have buttons for illegal floors but this elevator isn't real!
     # If the new floor is different to the current floor, tell the elevator where to go

     x = 10 # In this case the number of floors in the building doesn't change
            # but is, any way, a feature of the building and not the method
            # Consider whether this should be a constant in the class

     puts "The elevator does not go to that floor" if x > 10
     if x < 10
       puts "going to floor #{x}"
     end

     # MM: The logic of the above statements looks confused to me. You have two
     # MM: independent 'if' tests of the same variable, consider if..else instead

     # MM: This method should also set the state in response to calling the elevator
     # MM: shouldn't it?

     # MM: This very much suggests to me that the Elevator itself is a separate entity
     # MM: which should have it's own state & behaviour. Maybe you should break out
     # MM: Elevator into a new class that the Building class makes use of.

   end

   def time_passes
     # Is the elevator on the floor it has been called to?
     # If not move it one floor towards the target floor
     # If the elevator has reached it's target floor, print a message
         if @new_floor == @elevator_target_floor
         puts "elevator has arrived at your floor"
      end
   end


   def output_state
     # print out where the elevator is
     # if the elevator isn't at it's target floor print out whether it's heading up or down
     puts "floor " + 0.to_s + " is where the elevator is at"
     if @elevator_on_floor != @new_floor
       puts "elevator is going up"  # MM: but what if it's going down?
   end
 end

 my_building = Building.new

 #
 # This part is the "game"
 #
 # On each move you can either call the elevator to a floor by typing in the floor number
 # or simply allow the elevator to carry on its journey. Use ^d to exit (do you know why that
 # works?)
 #

 while line = gets
   line.chomp!

   if line =~ /d+/
     puts my_building.call_elevator_to_floor( line.to_i )
   end
  
  puts time_passes 
  puts output_state # MM: since both of these methods use 'puts' to output to the console
                    # MM: you don't need the puts here. Just call the methods
 end