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Smalltalk. Mark Colangelo CMSC-631, Fall 2002 10 December 2002. History of Smalltalk. Alan Kay designed and build the first OOP-based personal Computer called FLEX in 1967-68 In 1967 Simula 67 was designed

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smalltalk

Smalltalk

Mark Colangelo

CMSC-631, Fall 2002

10 December 2002

history of smalltalk
History of Smalltalk
  • Alan Kay designed and build the first OOP-based personal Computer called FLEX in 1967-68
  • In 1967 Simula 67 was designed
  • In 1972 Alan Kay and other and XEROX PARC Created Smalltalk 72 with roots tied to Simula 67
  • Followed by Smalltalk 76 (Completely OOPL)
  • Followed by Smalltalk 80 which became available as the first commercial release of Smalltalk
smalltalk in the real world
Smalltalk in the Real World
  • Financial
    • Chubb
    • Chrysler
    • Dunn and Bradstreet, several other
  • Manufacturing and Engineering
    • Texas Instruments
    • Romax (Simulation Software)
free implemenations of smalltalk
Free Implemenations of Smalltalk
  • Squeak (Smalltalk for Win , Mac and others)
    • http://www.squeak.org/download/index.html
  • GNU Smalltalk (Unix systems only)
    • http://www.gnu.org/software/smalltalk/smalltalk.html
installation of squeak
Installation of Squeak
  • Installation of Squeak is trivial
  • Download zip file
    • Squeak3.2.image
    • Squeak3.2.changes
    • SqueakV3.sources
    • Squeak VM for your system, version 3.2
  • Doubleclick Squeak image. No other installation is required
exending hello world
Exending Hello World

hello

1 to: 3 do: [:i | (Transcript show: \'Hello World\') cr]

Gives:

Hello World

Hello World

Hello World

adding logic to hello world
Adding Logic to Hello World

hello: times

(times > 100)

ifTrue: [ Transcript show: \'You will get bored!\'] ifFalse: [1 to: times do: [:i | (Transcript show: \'Hello World\') cr]]

final hello world
Final Hello World

hello: times say: text

(times > 100)

ifTrue: [ Transcript show: \'You will get bored!\'] ifFalse: [1 to: times do: [:i | (Transcript show: text) cr]]

syntax observations
Syntax Observations
  • Any variable can store any object. Object keeps track of what it is.
  • Could pass an integer into the text parameter. No error until the Transcript tried to show it.
messaging
Messaging
  • Always pass messages to an object
  • the colon syntax for parameter passing looks a lot like the colon syntax for loops--and logic, for that matter. That\'s because it\'s exactly the same.
  • hello:say, ifTrue:ifFalse: and to:do are all messages.
blocks of code are objects
Blocks of Code are Objects
  • [:i | (Transcript show: text) cr] is an object
  • Code block can be passed as an argument to to:do:
  • Transcript is a global variable that contains an object which understands the show: message.
  • In addition to show:, the Transcript object understands the message cr, which puts a newline in the Transcript window.
references
References
  • Smalltalk home page
    • www.smalltalk.org
  • Squeak home page
    • www.squeak.org
  • Smalltalk Industry Council home page
    • www.whysmalltalk.com
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