Introducing Objects in Squeak

1. Introducing Objects in Squeak Mark GuzdialGeorgia Tech

2. Story • Why Squeak? • How the course CS2340 Objects and Design is assembled • Examples of students assignments • How we use the CoWeb

3. Squeak • Smalltalk-80 running on modern machines (over 30 platforms) • http://www.squeak.org • Supporting wide range of media: Flash, MIDI, AIFF/WAV, MPEG • Open-source • Alan Kay, Dan Ingalls, Ted Kaehler from original Xerox PARC LRG plus Wonderful additions • Apple to Disney to Viewpoints Researchhttp://www.squeakland.org

4. Breaking the Lines

5. The Subversive Reason for Squeak • What if Steve Jobs and Bill Gates got it wrong? • What if the Xerox PARC idea of the personal computer was bigger than MacOS and Windows (and X-Windows and Gnome and…)? • In Squeak, you have what Jobs saw. LITERALLY THE EXACT SAME BITS? • Can you see what he missed?

6. Teaching Squeak • Squeak is the language of our required Sophomore level course on Objects and Design (140-250 students per term) • Focus on OOA/D/P and User Interfaces • Semester-long team projects • Leverage Squeak’s multimedia support to do interesting things

7. Content of Class • Focus on OOA, OOD, OOP • OOA: CRC Cards • OOD: UML Class Diagrams • OOP: Squeak • User interfaces: Building, design, evaluation • Cap of languages focus in our curriculum (follow-on to Languages and Translation)

8. Structure of Class • Students have a major, team-based project • Spring 2001: Build a map of Georgia Tech, based on information harvested from the Web • Eventually, grow it so that you can provide a 3-D tour of an IMAGINARY campus with vocal instructions • Lectures are available to provide students with theory, examples, issues • Students tend to stop coming very much to lecture past 3/4 point • One morning, SEVEN students…

9. Grading Policy • 25% Midterm • 10% Quizzes (4) (on coding) • 35% Final • 30% Project Assignments (7 of them)

10. On the CoWeb… • Definition of project • Milestones (Turn-ins) - ALL OF THEM • Roughly every two weeks • First one is individualized, all others are team-based • FAQs, links to external resources, etc. • Strongly recommended: Who’s Who page • Later: Cases, Surprises, Exam Reviews…

11. Project This Semester • Interactive Maps • P1 (individual): Draw a simple map with routes • P2 (team): Make it interactive with buildings • P3: Design everything • P4, P5: Whole campus and provide routes • P6: Make the map show up in Wonderland (3-D) with user-definable tours • P7: Provide a big tour for an imaginary campus (but don’t change code)

12. Project Last Semester • Text-based adventure games (Interactive Fiction) • P1 (individual): Build a pattern matcher that will work for (simple) natural language • P2 (team): Implement simple adventure game • P3: Design everything • P4, P5: Add features like Web access, daemons, interactive people • P6, P7: ANY API YOU WANT. Make the adventure game show up in Wonderland • P7: Build a game, but can’t change the code (without justification)

13. Philosophy of the Course • The course is on design, for novice designers • “If you know UML, Corba, COM, and XP already, great. Most people here don’t.” • But there’s a big focus on learning, not just lecturing. • Students have to implement your designs — live in them. Figure out where they’re bad • The course isn’t explicitly on programming in Squeak, but implicitly (to provide design feedback), it is. Quizzes focus on Squeak programming

14. Why Squeak? • Why not Java? Why not C++? • Marvin Minsky: “If you only know something in one way, you don’t know it at all.” • Faculty agreed that you should see something not C-based • Other reasons: • Great for UI • Different model for programming: Can’t use emacs • All the sources are there for everything

15. Why this class can be aggravating • It’s not about job skills, per se • No Delphi or Visual Basic here • Few job postings for Squeak these days (but increasing number for Smalltalk) • It’s about ways of thinking that are core to CS, about ways of designing programs • About where the core ideas of computers today came from • It’s about designing, critiquing designs, making tradeoffs, and making choices

16. Approach of Book (and elsewhere) • Concrete before Abstract • Build things before design them • Learning involves testing and failure • You have to try things in Squeak • Generation and Inquiry, over Transmission • There is no Squeak API • But there are lots of great tools for poking through the system • We'll teach the tools to help you learn how to figure it out for yourself

22. CoWeb:Collaborative Websites • Based on Ward Cunningham’s WikiWiki Web • Hence it’s “other” name: Squeak Wiki -> Swiki • Simple system: • It’s a website • Where any user can edit any page (caveat “locks”) • And any user can create new pages

23. Using the CoWeb

24. Features to support collaboration:Recent Changes and Attachments

25. We save everything, But it’s mostly social Security

26. Use in CS2340:HCI Review

27. HCI Review

28. Other uses: • Midterm and final exam reviews • Glossaries • Case libraries