1. A clean, innovative, open-source
Smalltalk
http://www.pharo-project.org/
Serge Stinckwich
Serge.Stinckwich@esug.org

2. 1 Smalltalk Syntax
2 Smalltalk object model
3 Pharo, an open-source Smalltalk

3. 1 Smalltalk syntax

4. What are the keywords ?
How do you build
expressions ?

5. Almost no keywords

6. Syntax for litterals
1 -10 30
3.14156 1e-10 -1.4e4
$A $z
‘Hello World’
#(1 2 3 4 5)

7. “A comment is a sequence of
characters surrounded by
quotation marks.”

8. Assignement
x := 3.
y := ‘Hello world’.
z := x+4.

9. 6 pseudo-variables
nil, true, false
self, super, thisContext

10. Everything happens
by message sending

11. (1) Unary message

12. receiver message.

13. 20 factorial

14. 2432902008176640000

15. ‘Esope reste et se repose’
reversed

16. ‘esoper es te etser eposE’

17. ‘12345’ isAllDigits

18. true

19. ‘Quelle est ma longueur ?’
size

20. 23

21. ‘foobar’ first

22. $f

23. (2) Binary Messages

24. aReceiver aSelector
anArgument

25. 3+4

26. 7

27. ‘Bonjour ’, ‘monde’

28. ‘Bonjour monde’

29. 2@3

30. 2@3

31. (3) Keywords Messages

32. 12 between: 8 and:15.

33. 8 < 12 < 15 ?

34. true

35. #(1 4 9 16 25) at: 3

36. 9

37. aString.substring(2, 5) aString copyFrom: 2 to: 5
ColorValue hue: a
new ColorValue(a, b, c)
saturation: b value: c
DateAndTime year: a day:
new DateAndTime(a, b, c)
b timeZone: c
Easier to document the semantic role
of arguments with keywords messages.

38. (Msg) > Unary > Binary > Keywords

39. Messages cascading

40. myBirthday := Date new.
myBirthDay setYear: 1967.
myBirthDay setMonth: 5.
myBirthDay setDayOfMonth: 10.

41. myBirthday := Date new;
setYear: 1967;
setMonth: 5;
setDayOfMonth: 10.

42. The
End

43. if ... then ... else ?

44. Weather today isRaining
ifTrue: [self takeMyUmbrella]
ifFalse: [self takeMySunglasses]
ifTrue:ifFalse is sent to an objet: a boolean

45. Closures
[3+4]
[‘Bonjour’ size. 3+4.
#(1 2 3 4) at:2]

46. A block (lexical closure) is a Smalltalk
object, whose value could be evaluated in
the future.
A block is evaluated by sending the
message value.

47. [1+2] value. ⇒ 3

48. Block could be parametrized
[:param1 :param2 ... | statements]

49. [:x | x+1] value:2.
[:x :y | x,y] value:’Bonjour’
value:’monde !’.

50. Dynamic binding
Postponing selection of an operation until
execution time
aCondition
ifTrue:[y:= 3]
ifFalse:[y:= #(1 2 3)].
y printOn: someStream.
Many printOn: methods,
compiler can’t preordain the choice.

51. Dynamic binding enables
polymorphism

52. Where is implemented
ifTrue:ifFalse: ?

53. Where is implemented
ifTrue:ifFalse: ?
True>>ifTrue:aBlock1 ifFalse: aBlock2
^aBlock1 value
False>>ifTrue:aBlock1 ifFalse: aBlock2
^aBlock2 value

54. Build your own control
structure !
7 ifSeven:[Object inform: ‘Its seven’]
Number>>ifSeven:aBlock
self=7 ifTrue:[^aBlock value]

55. Iterations

56. [Weather today isRaining]
whileTrue:[self doNotGoOutside.
self readAGoodBook]

58. Array
| life |
life := #(calvin hates suzie).
life at:2 put:#loves.
life. ⇒ #(#calvin #loves #suzie)
life first. ⇒ #calvin
life last. ⇒#suzie
life indexOf:#calvin. ⇒ 1
life indexOf:#asterix
ifAbsent:[Transcript show:’Je ne
connais pas’].

59. Set
s := Set new.
s add:1.
s add:2.
s add:2.
s. ⇒ a Set(1 2)

60. Interval
-10 to:10. ⇒ (-10 to: 10)
(-10 to:10) at:2. ⇒ -9
(-10 to:10) at:2 put:3.
⇒ erreur

61. OrderedCollection
distributions := OrderedCollection new.
distributions add:’Slackware’;
add:’Fedora’; add:’Ubuntu’.
distributions. ⇒ an
OrderedCollection('Slackware' 'Fedora' 'Ubuntu')
distributions remove:’Fedora’.
distributions. ⇒ an
OrderedCollection('Slackware' 'Ubuntu')

62. OrderedCollection
distributions addFirst:’Debian’.
distributions addLast:’RedHat’.
distributions. ⇒ an OrderedCollection('Debian'
'Slackware' 'Ubuntu' 'RedHat')
distributions add:’Mandriva’ afterIndex:2.
distributions. ⇒ an OrderedCollection('Debian'
'Slackware' 'Mandriva' 'Ubuntu' 'RedHat')

63. Collection enumeration
A collection contains a lot of elements.
Enumerate a collection is browsing the collection
and running a statement for each element:
do:, select:, reject:
collect:, inject:

64. Enumeration messages are polymorphic
=
they work whatever the collection is

65. do:
Evaluate the block for each element of the
collection.
total := 0.
a := #(1 2 3 4 5 6).
a do:[:unElement | total := total +
unElement]

66. select:
Evaluate the block for each element of the
collection and return a collectiof the items of the
same class containing elements whose evaluation
return true.
a := #(1 2 3 4 5 6).
a select:[:unElement| unElement even]
Return : #(2 4 6)

67. detect:
Evaluate the block for each element of the
collection and return the first element that
evaluate as the block value as true.
a := #(1 2 3 4 5 6).
a detect:[:unElement | unElement>3].
Return : 4.

68. 2 Smalltalk object model

69. Classe Rectangle
Rectangle
width
height
area
...

70. Object subclass: #Rectangle
instanceVariableNames: 'width height'
classVariableNames: ''
poolDictionaries: ''
category: 'Exemples-Heritage'

71. Rectangle>>width: w
width := w
Rectangle>>height: h
height := h
Rectangle>>width
^width
Rectangle>>height
^height
Rectangle>>area
^ width*height

72. Classe
ColoredRectangle
ColoredRectangle
width
height
color
area
...

73. A colored rectangle is like a rectangle but
with a color ...

74. Operations that can be done a rectangle,
can also be done on a colored rectangle
(e.g surface calculus)

75. a ColoredRectangle isa Rectangle

76. Rectangle subclass: #ColoredRectangle
instanceVariableNames: 'color'
classVariableNames: ''
poolDictionaries: ''
category: 'Exemples-Heritage'

77. ColoredRectangle>>color
^color
ColoredRectangle>>color:
aColor
color := aColor

78. Class inheritance
Rectangle
width
height
area
...
ColoredRectangle
color
...

79. a := Rectangle new.
a width:10.
a height:50.
a width. ⇒ 10
a height. ⇒ 50
a area. ⇒ 500

80. b := ColoredRectangle new.
b width:10.
b height:50.
b color: Color blue.
b width. ⇒ 10
b height. ⇒ 50
b color. ⇒ Color blue
b area. ⇒ 500

81. Rule 1
Everything is an object
Rule 2
Every object is an instance of one
class
Rule 3
Every class has a super-class
Rule 4
Everything happens by message
sending

82. Classes are also
objects !
1 class⇒ SmallInteger
20 factorial class ⇒
LargePositiveInteger
‘Hello’ class ⇒ ByteString
#(1 2 3) class ⇒ Array

83. Every class has a
superclass
Integer superclass ⇒ Integer
Number superclass ⇒ Magnitude
Magnitude superclass ⇒ Object

84. doesNotUnderstand:

85. If a class is an object, every
class should be also an
instance of a specific classe.
Metaclasses !

88. Metaclasses hierarchy is
parallel to class hierarchy

90. Every metaclasses is
instance of Metaclass

91. The metaclass of
Metaclass is an
instance of
Metaclass

93. How many classes in
the system ?
Object allSubclasses size

94. How many abstract
methods in the system ?
Object allSubclasses do:
[:aClass| aClass methodDict keys
select: [:aMethod |
(aClass>>aMethod)
isAbstract ]]

95. What is a dynamic
language ?
Dynamic typing: greater polymorphism
Metaprogramming (metaclasses):
allow language itself to be dynamically changed
allow hooks into object life cycle and method calls
Work with code as easily as data
Closures
Higher-order programming

96. Readability
Shorter code is easier to read and maintain and
refactor
Need balance between cryptic and expressive

97. square
^self*self
public int square(int x) {
return x * x;
}

98. button on: #mouseDown send:
#value to: [Object inform: 'You
clicked me'].
button.setOnClickListener(new
View.OnClickListener() {
public void onClick(View view) {
(Button) view.setText(""You Clicked
Me!")
}
});

99. 3
Pharo, an open-source
Smalltalk

101. In a nutshell
Pharo = language + IDE
Pure object-oriented programming language
(Smalltalk)
Dynamically language and trait-based
Open and flexible environment
Used Monticello for versionning (Metacello
planned for 1.1)

103. iPhone

104. Pharo class Browser

105. other Pharo tools

107. Polymorph UI
Polymorph provides support for selectable UI
themes in Morphic, extra widgets to support a
consistent look&fell, a framework for easily
creating UI in code.
Standard UI in Pharo

109. Demo of Pharo
Simple examples
BlinkMorph example
Skins support
MultiMorph UI (UITheme examples)

110. Tests !
9179 unit tests includes in Pharo 1.0
9144 passes
20 expected failures
15 failures
0 errors

111. Everybody can help
Reporting bugs
Confirming bugs
Writing tests
Writing examples
Writing comments
Simple contributing fixes
Deep discussion...

112. Community Process
FIX/
ENHANCEMENT Discussed on
In PharoInbox or Discussed
Changesets on Mailing- BUG
list
Described
Described
BUG Tracker
Discussed on
Other
version
Integrated Rejected

113. http://www.pharobyexample.org/
Pharo by example vol. 2 on preparation

114. Pharo Sprints
May 2008 Bern (Switzerland)
July 2009 Bern (Switzerland)
October 2009 Lille (France)
November 2009 Buenos Aires
(Argentina)

115. Thanks Hans Beck
Matthew Fulmer
Hilaire Fernandes
Julian Fitzell David J Pennell
Alexandre Bergel
Tudor Girba Joseph Pelrine
Cédric Beler
Sean Glazier Alain Plantec
Torsten Bergmann
Norbert Hartl Damien Pollet
Matthias Berth
Dale Henrichs Lukas Renggli
Ralph Boland
Reinout Heeck Jorge Ressia
Noury Bouraqadi
Eric Hochmeister Mike Roberts
Brian Brown
Keith Hodges Robert Rothwell
Gwenael Casaccio
Henrik Sperre Johansen David Rotlisberger
Damien Cassou
Pavel Krivanek Michael Rueger
Nicolas Cellier
Adrian Kuhn Bill Schwab
Gary Chambers
Adrian Lienhard Niko Schwarz
Miguel Coba
Andreas Leidig Igor Stasenko
Gabriel Cotelli
Mariano Martinez Peck Francois Stephany
Carlos Crosetti
Dave Mason Serge Stinckwich
Cyrille Delaunay
John McIntosh Mathieu Suen
Simon Denier
Johnaton Meichtry Lawrence Trutter
Marcus Denker
Eliot Miranda Andrew Tween
Ramiro Diaz Trepat
Hernan Morales Durand Martin von loewis
Stéphane Ducasse
Philipp Marshall Juan Vuletich
Morales Durand Hernan
Jannick Menanteau Steven Wirts
Stephan Eggermont
Yann Monclair Hernan Wilkinson
Luc Fabresse
Oscar Nierstrasz

116. Join Us!
Creating good energy, software quality,
learning and having fun
http://pharo-project.org

117. Cộng đồng Smalltalk Việt
Smalltalk-VN mailing-list :
http://lists.squeakfoundation.org/
mailman/listinfo/smalltalk-vn
Smalltalk flyer in vietnamese
EToys in vietnamese

118. Occam's razor: "entities should not be
multiplied beyond what is necessary" (entia
non sunt multiplicanda praeter necessitatem)
the simplest solution is usually the
correct one.

119. Thank you for your
attention.
Cám ơn sự quan
tâm của bạn.