Smalltalk
Serge Stinckwich
(Serge.Stinckwich@esug.org)

The origin of Smalltalk
Alan Kay’s Dynabook project (1968)
Alto —!Xerox PARC (1973)

Smalltalk today

Smalltalk today

Smalltalk today

Smalltalk today

Smalltalk today

Squeak resources
www.squeak.org www.seaside.st
Downloads and links One-click image
SqueakByExample.org
Free download — Print-on-demand

Getting started

Everything is an object

Everything happens by sending
messages

Running Squeak

Do it, print it
You can evaluate any
expression anywhere
in Smalltalk

Standard development tools

Debuggers, Inspectors, Explorers

Syntax in a Nutshell

Three kind of messages
5 factorial
Unary messages Transcript cr
Binary messages 3+4
Keyword messages
3 raisedTo: 10 modulo: 5
Transcript show: 'hello world'

A typical method in the class Point
Method name Argument Comment
<= aPoint
! quot;Answer whether the receiver is neither
! below nor to the right of aPoint.quot;
! ^ x <= aPoint x and: [y <= aPoint y]
Return Block
Binary message
Instance variable Keyword message
(2@3) <= (5@6) true

Statements and cascades
Temporary variables
Statement
| p pen |
p := 100@100.
pen := Pen new.
pen up.
pen goto: p; down; goto: p+p
Cascade

Control structures
Every control structure is realized by message sends
4 timesRepeat: [Beeper beep]
max: aNumber
! ^ self < aNumber
! ! ifTrue: [aNumber]
! ! ifFalse: [self]

Control structures
Every control structure is realized by message sends
4 timesRepeat: [Beeper beep]
Boolean
ifTrue:ifFalse:
max: aNumber True False
ifTrue:ifFalse: ifTrue:ifFalse:
! ^ self < aNumber
! ! ifTrue: [aNumber]
! ! ifFalse: [self]
ifTrue: t ifFalse: f ifTrue: t ifFalse: f
^ t value ^ f value

Creating classes
Send a message to a class (!)
Number subclass: #Complex
! instanceVariableNames: 'real imaginary'
! classVariableNames: ''
! poolDictionaries: ''
! category: 'ComplexNumbers'

Smalltalk ressources
• Mailing-list : http://
lists.squeakfoundation.org/mailman/listinfo/
smalltalk-vn
• Smalltalk flyer translated in Vietnamese
• http://community.ofset.org/wiki/Squeak