	CS 535 Object-Oriented Programming & Design Fall Semester, 2001 Introduction
	Lecture Notes Index Next © 2001, All Rights Reserved, SDSU & Roger Whitney San Diego State University -- This page last updated 04-Sep-01

Contents of Doc 1, Introduction

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

Software Productivity Research, Inc. (www.spr.com)


Doc 1, Introduction Slide # 2

Introduction

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

Contains features not covered elsewhere in curriculum


Doc 1, Introduction Slide # 3

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 # 4

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 # 5

Smalltalk Influences
Object-Oriented Programming

GUI

Macintosh
Windows

Refactoring

Extreme Programming


Doc 1, Introduction Slide # 6

Versions of Smalltalk
VisualWorks

VisualAge for Smalltalk

Squeak

Dolphin
Smalltalk MT

Smalltalk X

Smallscript

PocketSmalltalk


Doc 1, Introduction Slide # 7

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 # 8

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

As you use Smalltalk the image file will change. When you make changes to code they are saved in the change file. At some point you will want to start over with a clean copy of the image. Before you use VisualWorks make a backup copy of the image file. When you want a fresh copy of the image, use copies of the backups.

parcels

Code bundles
Doc 1, Introduction Slide # 9

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 # 10

Starting VisualWorks on Macintosh
Method 1

Drag and drop the image file on the visual application

Method 2

Double click on the image file

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 # 11

Some VisualWorks Environment

It is hard to explain on paper how to use GUIs. The best thing is to use the GUI and have an expert user nearby. The following may help you get started. For more information see Chapter 1 The VisualWorks Environment, VisualWorks Application Developer’s Guide, doc/vwadg.pdf in the VisualWorks installation.

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 # 12

Windows on Startup

Launcher

The Launcher is the main window in VisualWorks. It is your main starting point in the VisualWorks IDE. Do not close this window. We will come back to this window.

The welcome to VisualWorks window contains some useful information. Ivan Tomek’s introduction will lead you through much of Smalltalk. Try going through it.


Doc 1, Introduction Slide # 13

Lesson Runner

Lesson runner leads you through Smalltalk syntax, some of the Smalltalk classes and some tools.


Doc 1, Introduction Slide # 14

Workspace
Workspaces are good places to try out Smalltalk code. There are two ways to open a Workspace from the Launcher. First you can click on the Notepad icon in the Launcher. The second way is to select the “Workspace” item in the Tools menu in the Launcher.
.

There are a number of interesting things one can do with the Workspace. The most important is to execute code. The code can be run with four different options: do it, print it, inspect it, and debug it. To run the code first select the code you wish to run. The code should now be highlighted. Now run the code using the option you wish by: clicking on the corresponding icon, selecting the corresponding item in the “Smalltalk” menu, or using the short-cut keys.

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 # 15

Examples

We will go through a few examples. To keep the images small, only part of the windows will be shown.

Do it

In a workspace window type: Dialog warning: ‘Hello World’. Select the text and then run the code with "do it". In the window above, “do it” was done via the icon. When this is done you will see the following dialog. When code is run via do it, the code is first compiled to Smalltalk byte code. The byte code is translated to machine code by the JIT, which is then run.


Doc 1, Introduction Slide # 16

Print it
For the following example, the workspace tool bar was closed to make the graphic a bit smaller. This is done using the option menu in the workspace.

In a workspace, type the text: 30 factorial. Now try selecting the text and running the code using “do it”. Seemingly nothing happens. The code is run, but there is no indication of this. Now run the code using “print it”. This will run the code and print the result of the code in the workspace. As you can see below, the result is a large integer. Smalltalk can handle any integer that your machine as memory for.


Doc 1, Introduction Slide # 17

Using the Transcript

Smalltalk has a special output window called the Transcript. The text pane in the Launcher is the Transcript. You can write to the Transcript from your code. While in some languages this is done a lot in debugging, Smalltalk provides a better way to debug.

Type the code shown above in a workspace and run the code using “do it”. The following will appear in the Transcript.

Doc 1, Introduction Slide # 18

Exiting from VisualWorks

To exit from VisualWorks, select the “Exit VisualWorks” item in the “File” menu of the Launcher.

You will get a dialog asking if you want to save the image. Saving the image put the current state of the image on disk. When you restart the image it will be in the same state as when you saved it. Normally you want to save the image. If you don’t save the image it takes some effort to recover your work.

Saving your image changes the state of the image on disk. If you save the image under the name visual, then you will lose the original state the image. So save the image under a different name. When you save an image “.im” is appended to the end of the name. Hence there is no need to put the “.im” ending on the name.

Doc 1, Introduction Slide # 19

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 # 20

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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