	CS 535 Object-Oriented Programming Spring Semester, 2003 Introduction
	Lecture Notes Index © 2003, All Rights Reserved, SDSU & Roger Whitney San Diego State University -- This page last updated 21-Jan-03

Contents of Doc 1, Introduction

References
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. (www.spr.com)


Doc 1, Introduction Slide # 2

Introduction

Goal
Understand how to use classes & objects in code

Syntax of language is easy

How to create code that is:

Understandable
Modifiable
Maintainable
Reusable


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

Logic
Methods

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

Best language to learn object-oriented thinking

Productivity Gains

Software Productivity Research Study

Language	Lines of code/function point
Smalltalk	21
Ada 95	49
Java	53
C++	53
COBOL	107
C	128


Doc 1, Introduction Slide # 6

Why Smalltalk

Experience with dynamic typed language

Reading Code

Tool Support in software development


Doc 1, Introduction Slide # 7

Learning Smalltalk

Smalltalk language syntax


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

Smalltalk Programming Environment


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

Smalltalk Class Library

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

Object-oriented thinking

This is the hardest part

Smalltalk culture

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?
Dynabook

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

GUI

Macintosh
Windows

Refactoring

Extreme Programming


Doc 1, Introduction Slide # 10

Versions of Smalltalk
VisualWorks

VisualAge for Smalltalk

Squeak

Dolphin
Smalltalk MT

Smalltalk X

Smallscript (.NET Smalltalk)

PocketSmalltalk


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:

Windows
Macintosh
Unix

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

VisualWorks

Parts of VisualWorks
Executable Virtual Machine (visual, visual.exe)

This is the VM that interprets Smalltalk bytecode

visual.sou

Source code for most of class library

visual.cha

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

visual.im

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

parcels

Code bundles
Doc 1, Introduction Slide # 13

Starting VisualWorks

See the class wiki for instructions on downloading VW 5i4

Before Starting VisualWorks
Before you start VisualWorks make a copy of visual.im

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
Type:

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/smalltalk/vw7nc/image/visualnc.im to a local directory

Change permissions so you have write permission on the local copy

Set the VISUALWORK environment variable

setenv VISUALWORKS /opt/smalltalk/vw7nc (csh or tcsh)

set VISUALWORKS='/opt/smalltalk/vw7nc': (sh)

Add the following to you path

/opt/smalltalk/vw7nc/bin/solaris

To start the image:

visual imageName


Doc 1, Introduction Slide # 17

Some VisualWorks Environment

VisualWorks uses three logical buttons

Select button

Selects objects and text

Operate button

Opens a menu with context-sensitive commands

Window button

Opens a menu with window commands

Mapping Logical to Physical Mouse Buttons

	3-Button	2-Button	1-Button
Select	Left button	Left Button	Button
Operate	Right button	Right button	Ctrl+Button
Window	Middle button	Ctrl+Left button	command+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

Launcher

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


Doc 1, Introduction Slide # 19

Lesson Runner


Doc 1, Introduction Slide # 20

Workspace

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 # 21

Examples

Do it


Doc 1, Introduction Slide # 22

Print it


Doc 1, Introduction Slide # 23

Using the Transcript

Doc 1, Introduction Slide # 24

Exiting from VisualWorks

Doc 1, Introduction Slide # 25

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.


Doc 1, Introduction Slide # 26

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.
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