cs2340: Objects and Design

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cs2340 Objects and Design

• Fall 2006

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Reading

• Required Text
• Object Design Roles, Responsibilities, and
  Collaborations, Rebecca Wirfs-Brock, 2003
• Recommended Text
• The CRC Card Book
• Supplemental Reading
• Available on the CoWeb/Web Page
• http//web.engr.oregonstate.edu/budd/Books/oopint
  ro3e/info/ReadMe.html
• Smalltalk Books at http//www.iam.unibe.ch/ducas
  se/FreeBooks.html

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Online Resources

• The CoWeb
• http//coweb.cc.gatech.edu/cs2340
• An editable website with over 5000 pages
• The primary source of information for this class
  Whos who schedule, software, assignments, etc.
• The Newsgroup
• git.cc.class.cs2340
• Used primarily for announcements and questions
• Readings
• Off Class website

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Learning Goals (page 1)

• Object-Oriented Programming
• But, didnt we learn that in cs1322?
• No, you learned how to program with objects.
• Its not the same thing.
• In this class, you learn good object-oriented
  programming style, with emphasis on ANALYSIS and
  DESIGN
• To help you learn OO programming, you will learn
  a new language - Smalltalk

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Why Smalltalk?

• Smalltalk is the canonical example of a
  class-based OO language
• Many of the important concepts in OO programming
  become clear in Smalltalk
• Everything is an object
• Instance vs. Class
• Message Passing
• As a late-bound language, Smalltalk has
  high-level tools to help you be a better OO
  programmer

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Where is Squeak?

• This semester we will use a commercial Smalltalk
  environment, Cincom Visualworks.
• Visualworks is free for non-commercial use and
  has excellent documentation (albeit not oriented
  towards beginners).
• Look for manuals in the doc directory of the
  installation.

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Downloading Visualworks

• Current version is 7.4nc
• Available from company website at
• http//smalltalk.cincom.com/downloads/index.ssp?co
  ntentsmalltalk

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Learning Goals (page 2)

• Object-Oriented Process
• Writing good OO code often requires doing a good
  job with the design beforehand
• Object-Oriented Analysis (OOA)
• Class Responsibility Collaboration Cards
• Use Scenarios and CRC Cards to get your design on
  the right track
• Object-Oriented Design (OOD)
• UML
• Theory and Rules of Design
• Design Validation

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Learning Goals (page 3)

• User Interfaces (2 Orthogonal Topics)
• Programming GUIs in an OO manner
• Model View Controller (MVC)
• Visualworks model - Domain Model / Application
  Model - View - Controller
• Usability
• Just because a user interface is well designed
  from a programming standpoint does not mean that
  it is usable by others.
• Object-Oriented Programming (OOP)
• Smalltalk language
• Patterns/Idioms
• Object-Oriented Testing
• SUnit, Unit Test Theory (Review)

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Secondary Topics

• History of OO Programming
• Extreme Programming An OO software engineering
  method that has its roots in Smalltalk
• Virtual Machines and Garbage Collection Most OO
  languages use a virtual machine and garbage
  collection
• Comparing other OO Languages

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Grading Policy

• 2 Exams (45)
• Midterm - 20
• Final - 25
• Individual Assignments - 25
• Program 1 5 (An addition/ enhancement to
  existing code)
• Program 2 5 (An additional enhancement to
  existing code)
• HW 1 2 (Intro to Smalltalk)
• HW 2 5 (A small indiv design using CRC/UML)
• HW 3 8 (A larger group design with
  peer-review/critique)
• 6 Group Project Milestones (30)
• M1 and M2 - 4 each
• M3 8
• M4 6
• M5 5
• M6 - 3 each
• Extra Credit - 1-5
• Only available to those that do the programming
  assignments

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Programming Assignments

• The Goal
• To get you programming in Smalltalk
• Get some exposure to separating Model and View
• The first one is due soon, so get crackin on
  learning Smalltalk
• Work through the Visualworks on-line tutorial at
  their web site.

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Programming Assignment 1Extend the Sudoku Puzzle

• Sudoku
• Put digits 1-9 in every row, column, and region
• You are given the code for a rudimentary Sudoku
  puzzle and asked to extend it

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Programming Assignment 1End State

• Update the score
• Mark invalid cells

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Group Project Milestones

• Groups of 3-4
• Not 2 Thats too easy. You need to learn how to
  work in larger groups. Plus, your partner
  dropping would be BAD.
• Not 5 Thats either too easy (if your group
  functions well) or too hard (if your group
  functions badly).
• This semesters project Ectropic Port to
  Visualworks

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Ectropic

• A collaborative design environment implemented in
  Squeak.
• We will do a subset of this
• CRUD CRC Cards
• CRUD Scenarios
• CRUD Goals
• Tie CRC Cards to Scenarios to Goals
• Make it graphical
• Create a basic UML Class diagram from the CRC
  Cards

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Group Work

• Working in teams is tough dont underestimate it
  (Especially for those of you who did not take
  2335).
• Be careful about who gets on your team.
• Friends are a risky proposition
• Slackers will cost you loads of headache
• Work as a team
• Hold people accountable
• Dont just staple work together
• Bright idea Do the CRC Cards as a team

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Group Project Milestone 1

• M1 Getting Started
• Individual Code
• M2 Initial Design
• Create your team page on the CoWeb with members
  names
• Do a set of CRC cards and scenarios for Ectropic
• Mandatory Run it by a TA
• You must be able to step through the scenarios
  using your CRC cards
• Preferably, all group members are there
• The TAs are there to help you understand CRC
  cards

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Group Project Milestones 2-6

• M3 Final CRC Analysis and Scenarios, Model
• Mandatory Run it by a TA to make sure you are on
  the right track
• M4 View/Controller
• M5 UI Evaluation
• M6 The Twist

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Group Project Milestone 6

• M6 The Secret Twist
• If you have done a good job with your design, you
  should be able to adapt it easily to new
  requirements.
• So, at the end of M5, M6 details will be
  revealed.
• In the past, this has involved things like
  putting it on the Web or making things compatible
  between groups

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Doing Well in this Class

• Come to Lecture
• We will do live code demonstrations to help you
  get started with programming.
• If you have a laptop, try out the code being
  shown. Thats a great way to learn.
• Learn Smalltalk quickly, start now.
• See your Teaching Assistants
• In particular, do it early to get the CRC cards
  right
• They can help you with coding.
• Show them what you are planning to turn in
  theyll advise you on making it better. SERIOUSLY

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Doing Well in this Class

• Learn to Code in Smalltalk
• Do it early. Itll only hurt you to put it off.
• Use the resources available (lecture, book,
  CoWeb, TAs)
• Dont be afraid to come and see me if you need
  help. We are all transitioning from Squeak to
  Visualworks, so it will be a lot of fun for all.

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Why this Class can be Aggravating

• It is a project-based time-intensive class.
• Teamwork is hard
• You are learning a new language, a new
  environment, and a new paradigm for programming
  Thats tough.
• Smalltalk is not Java Dont try to use it as
  such. You will only get frustrated.

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Next on the Menu

• Programming in Smalltalk
• Using Visualworks