1. **** When you read this chapter take note of how Larman documents the use of GRASP. He links a message to its objects with a GRASP pattern name. Do this in your projects in this class.

   What is a pattern

   An Example Pattern: The Pizza Inversion Pattern [ pizza-inv.html ] (Ho Ho Only Serious).

   What is GRASP?

   (see GRASP below).

   17.1 UML vs Principles

2. * UML lets you communicate, recall, store ideas...
3. * Principles help you choose the right way to go, make decisions and choices.

   17.2 Object Design

4. ** OO design is about choosing who does what inside the computers.

   Figure 17.1 How it all fits together

   [ artifactrelationships.gif ]

   17.3 Responsibilities -- things that objects know how to do

   
   * The R in gRasp.
   **** Objects are little capsules of intelligence.
5. **** They know how and know what: they have operations and attributes.

   17.4 GRASP -- good ways to allocate responsibilities to objects

6. Exercise: name as many GRASP as you can from memory.

   Here [ 16answer.html ] are the 9 GRASP principles/patterns

   17.5 Connections

   17.6 Patterns

7. *** a workable resolution to a set of conflicting forces.
   * Patterns are the P in GRASP.
8. * A Pattern is a "good enough" way of solving a complex problem. It balances the competing forces in a sensible way. It has been used on at least three similar situations. Patterns are found and recorded not created.

9. * Patterns resolve a set of forces in a repeatable and useful way.

10. *** See inside cover of book.
11. See my notes [ patterns.html ]
12. See the famous [ wiki?CategoryPattern ]
13. See Brad Appletons Documents [ http://www.cmcrossroads.com/bradapp/docs/ ]

14. For more Patterns and discussions of patterns see [ wiki ] (The WikiWikiWeb).
15. Also checkout the Wikipedia entry [ GRASP_%28Object_Oriented_Design%29 ]

    17.7 Summary: process, responsibility metaphor, patterns, UML

    17.8 Short Example: Monopoly

16. Exercise: can you reconstruct this example without looking at the book?
17. By the way here is a first rough transcription of these figures into C++: [ testPlayMonopoly.cpp ]

    17.9 Applying GRASP

    17.10 Creator

18. * take note of suitable creators for an object.

    17.11 Expert

19. A very powerful idea.
20. *** Tends to incorporate parts of the domain model into the software design.

    17.12 Low Coupling

21. ***** Coupling has guided good software design for nearly 40 years.
22. + Reduce dependencies.

    17.13 Controller

23. **** Don't fill up user interface classes with domain/business stuff.
24. **** Separate the model and view by a controler.

    

    [ patterns.html#MVC ]

25. + Some people dislike use case/session controlers.
26. + View is often technology dependent and Controllers determined by the user's needs of the moment.
27. + The "model" or domain layer is independent of technology and inspired by the domain or business model.

    17.14 High Cohesion

28. **** Cohesion has guided good software design for nearly 40 years.
29. + Separate concerns into different classes.
30. + place responsibilities to give focussed objects.

31. + Ballancing cohesion and coupling is an art form.

    17.15 Resources

. . . . . . . . . ( end of section The GRASP Patterns) <<Contents | End>>

Questions and Answers

Example:

1. Does every A have a D?
2. Does every B Have a C?
3. Does every B have a D?
4. Does every A have a C?

Possble handout....

Next -- GRASP 1