I. Object-oriented design: a way to think about organizing programs
 A. goals
	-------------------
	 clients | impl
	-------------------
 B. responsibility-driven design method
  1. for each action, find an object to be responsible for it.
  2. CRC cards
   a. on front (spec)
-----------------------
	CRC CARDS

  ClassName          | Collaborators
  ---		     |
  Responsibilities   |
  ...		     |

-----------------------
   b. MVC example
--------------------------------------
 CRC CARDS for Model, View, Controller

  View               |   Controller
  ---		     |   Model
  Render the Model   |

  Transform coordinates


  Controller           |   View
  ---		       |   Model
  Interpret user input |
		       |
  Distribute control   |


  Model                |
  ---		       |
  Maintain problem info|
		       |
  Broadcast change     |
	notification   |
----------------------------------
   c. Lottery example
----------------------------------
  LottoCustomer         |
  ---		        |
  remember how much	|
	willing to lose	|
  play lottery some #   | Lottery
	of times	|

  Lottery               |
  ---		        |
  pick winning ticket	| WinningTicket
			| UniformDiscrete
  tell how much ticket	|
	has won		|

  Ticket                |
  ---		        |
  hold 7 distinct	|
	integers	|

  WinningTicket         |
  ---		        |
  (as in Ticket)	|
  tell number of matches| Ticket
	to a Ticket	|

  UniformDiscrete       |
  ---		        |
  remember how many to	|
	pick from	|
  give set of distinct	|
	numbers of a size
----------------------------------
   d. CRC cards on back (implementation design)
 C. exercises
  1. ATM banking machine
  2. A kitchen management system.