SDSU CS 535 Object-Oriented Programming
Fall Semester, 2003
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San Diego State University -- This page last updated 02-Sep-03

Contents of Doc 1, Introduction


VisualWorks Application Developer’s Guide, doc/vwadg.pdf in the VisualWorks installation. Chapter 1 The VisualWorks Environment.

Smalltalk Best Practice Patterns, Kent Beck

Object-Oriented Design Heuristics, Arthur Riel

Software Productivity Research, Inc. (

Doc 1, Introduction Slide # 2



Understand how to use classes & objects in code

Syntax of language is easy

How to create code that is:

Doc 1, Introduction Slide # 3
Main Idea in Object-Oriented Programming

Related data and operations belong together

Design Heuristic 3.3

Beware of classes with many public accessor methods

Many accessors indicate that related data and behavior are not being kept in one place

Doc 1, Introduction Slide # 4
Kent Beck’s Indicators of Good Style

Once and only once

Don’t repeat

Lots of little pieces

Rates of change

Don’t put two rates of change together

Don’t mix variables that change hourly with those that change monthly

Doc 1, Introduction Slide # 5
Why Smalltalk

Software Productivity Research Study
Lines of code/function point
Ada 95

Doc 1, Introduction Slide # 6
Why Smalltalk

Doc 1, Introduction Slide # 7

Learning Smalltalk

While Smalltalk syntax is simple it is not like C/C++/Java

Requires more effort to learn at first, but worth the effort

Smalltalk has a large library of useful code
Don't code without it

This is the hardest part

Smalltalker's have standard ways to code & solve problems
See Smalltalk Best Practice Patterns by Kent Beck

Doc 1, Introduction Slide # 8
Some History
1967 Simula-67

Language developed in Norway for simulations
Use classes and objects

Late 1960’s Alan Kay – Father of Personal Computer

Kay Ph. D. thesis addresses the question:
How will we interact with notebook size computers?

1970-80 Xerox Parc
Alan Kay, Dan Ingalls, Ted Kaehler and others work on Smalltalk
Small – Originally for children
talk - Code is to communicate

Doc 1, Introduction Slide # 9
Smalltalk Influences

Object-Oriented Programming




Extreme Programming

Doc 1, Introduction Slide # 10
Versions of Smalltalk


VisualAge for Smalltalk


Smalltalk MT

Smalltalk X

Smallscript (.NET Smalltalk)


Doc 1, Introduction Slide # 11
Smalltalk & Bytecode

Smalltalk is compiled to a bytecode for a virtual machine

Bytecode is same on all machines

VisualWorks has VM's for:


VisualWork’s virtual machine (VM) uses a JIT to compile bytecodes

Just-in-time compilers (JIT)
Compile bytecode to native machine code
Cache the native machine code
Run the native machine code
Usually runs faster than interpreting bytecode

Smalltalk started using just-in-time compilers in early 1980s

Doc 1, Introduction Slide # 12


Parts of VisualWorks

Executable Virtual Machine (visual, visual.exe)

This is the VM that interprets Smalltalk bytecode


Source code for most of class library


Source code for changes & new classes
Does not exist until after you first use VisualWorks

Bytecode of sources that are executed
At first the image will appear to be an IDE for Smalltalk


Code bundles

Doc 1, Introduction Slide # 13

Starting VisualWorks

See the class wiki for instructions on downloading VW 7.1

Before Starting VisualWorks

Before you start VisualWorks make a copy of

You will need it later

Starting VisualWorks on Windows

Method 1

Drag and drop the image file on the Visual application or visual.exe
Method 2

Double click on the image file
The first time you do this you may get a dialog asking for the application to run the image. Select visual. You will have to find it first. It is in the bin directory.

Doc 1, Introduction Slide # 14
Starting VisualWorks on Macintosh

Method 1

Drag and drop the image file on the visual application
Method 2

Double click on the image file

Doc 1, Introduction Slide # 15
Starting VisualWorks on UNIX

visual imageFilename &

where you need to replace imageFilename with the actual name of the image file you wish to run

You path has to be set to include the program visual

Doc 1, Introduction Slide # 16
VisualWorks on Rohan

Image requires ~9MegBytes of disk space

Copy /opt/vw71nc/image/ to a local directory

Change permissions so you have write permission on the local copy

Set the VISUALWORK environment variable

setenv VISUALWORKS /opt/vw71nc (csh or tcsh)

set VISUALWORKS='/opt/vw71nc'

Add the following to you path


To start the image:

visual imageName

Doc 1, Introduction Slide # 17

Some VisualWorks Environment

VisualWorks uses three logical buttons

Selects objects and text
Opens a menu with context-sensitive commands
Opens a menu with window commands

Mapping Logical to Physical Mouse Buttons

Left button
Left Button
Right button
Right button
Middle button
Ctrl+Left button

You should perform the action described in the next few pages. One learns what one does.

Doc 1, Introduction Slide # 18

Windows on Startup


Ivan Tomek’s Introduction is a good way to start to learn about Smalltalk

Doc 1, Introduction Slide # 19

Do it (ctrl-d)
Compile and execute the selected code
Print it (ctrl-p)
Same as "do it" but also prints the result of running the code
Inspect it (ctrl-i)
Same as "do it" but also opens an inspector window on the result of running the code

Debug it (ctrl-d)
Opens the debugger to allow you to step through the selected code. We will cover the debugger later.

Doc 1, Introduction Slide # 20


Do it

Doc 1, Introduction Slide # 21
Print it

Doc 1, Introduction Slide # 22

Using the Transcript

Doc 1, Introduction Slide # 23

Exiting from VisualWorks

Doc 1, Introduction Slide # 24

Some Text Editing Short Cuts

Selection shortcuts (double click)

To select text, use the following double-click shortcuts.
Double-click at start or end of a window to select all text in the window.
Double-click at start of line to select the line. Does not work on the first line.
Double-click at end of line to select the line. Does on work on the last line.
Double-click just after an opening (or just before the closing) of ' or [ or ( or " selects all text surrounded by the symbols.
Double-click inside a word or selector to select the word or selector.

Ctrl keys

Press at the same time the control key and the second key to:

<Ctrl> f inserts ifFalse: into the text.
<Ctrl> t inserts ifTrue: into the text.
<Ctrl> g inserts := into the text.
<Ctrl> d inserts today's date into the text.
<Ctrl> s (search or find) finds the next instance of the string in your copy buffer (last copied or cut string)
<Ctrl> e (replace) opens a replace dialog
<Ctrl> a (find) opens a find dialog
<Ctrl> c is equivalent to Copy,
<Ctrl> z will Undo the most recent text change,
<Ctrl> v is equivalent to Paste

ESC keys

Press and release the ESC key then press the second key to:

ESC b changes the selected text to bold.
ESC i changes the selected text to italic.
ESC u underlines the selected text.
When the letter is uppercase (B, I, U), the effect is reversed: ESC U removes underline, etc.
ESC + increases the font size of the selected text
ESC - decreases font size of the selected text
ESC followed by < or ' or " or [ or ( adds surrounding < ' " [ ( to the selected text.
ESC followed by <tab> selects the text just typed in
ESC x removes style changes to current selection and returns to default font.
Alt Keys

Alt keys are also used as menu accelerator keys. Since menu accelerator keys have priority the following keys may not work in all text windows.

<alt> a (again) repeats the last text change
<alt> A repeats the last text change for rest of text in window
<alt> c copies selected text into copy buffer
<alt> d (do it) compiles and executes selected text
<alt> f finds the next occurrence of the selected text
<alt> F finds the next occurrence of the text in the copy buffer
<alt> n finds the next occurrence of the selected text
<alt> p pastes the copy buffer into the current location
<alt> P pastes from the last 5 elements of copy buffer
<alt> z undoes the last edit

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2003 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA.
OpenContent license defines the copyright on this document.

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