Smalltalk Bar Camp Hanoi 2009

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

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

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

Smalltalk Bar Camp Hanoi 2009

by Stinckwich Serge

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