Introducing Objects in Squeak

Mark GuzdialGeorgia Tech

Story

Why Squeak?How the course CS2340 Objects and

Design is assembledExamples of students assignmentsHow we use the CoWeb

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

Breaking the Lines

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?

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

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)

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…

Grading Policy

25% Midterm10% Quizzes (4) (on coding)35% Final30% Project Assignments (7 of them)

On the CoWeb…

Definition of projectMilestones (Turn-ins) - ALL OF THEM

Roughly every two weeksFirst one is individualized, all others are team-based

FAQs, links to external resources, etc.Strongly recommended: Who’s Who pageLater: Cases, Surprises, Exam Reviews…

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)

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 WonderlandP7: Build a game, but can’t change the code (without

justification)

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

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

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

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

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

Using the CoWeb

QuickTime™ and aQuickDraw decompressor

are needed to see this picture.

Features to support collaboration:Recent Changes and Attachments

Security

We save everything,

But it’s mostly social

Use in CS2340:HCI Review

HCI Review

Other uses:

Midterm and final exam reviewsGlossariesCase libraries