1	Smalltalk Keith Alcock TCS DevSIG 3 February 2004
2	Contents Introduction: What is Smalltalk? Hands On: Dolphin Smalltalk Conclusion: Resources
3	Introduction: What is Smalltalk? Language Characteristics Implementation Commercial Open source
4	What is Smalltalk: Language Syntax object message noun verb (you scram) noun verb: object (you read: aBook) noun verb: object preposition: object (you give: theBook to: me) Incompatibilities ↑ for ^, ← for :=, {} for ##() in Squeak namespaces in VW Library 10,000s of methods, 1,000s of classes GUI development Portable across OSes, not Smalltalks Model View Controller (MVC) or Presenter (MVP) architecture Standard ANSI 1998 Errors and omissions Backward compatibility issues
5	What is Smalltalk: Characteristics Object oriented Single inheritance Zero or more protocols (interfaces) Garbage collected Dynamically typed Reflective (supports reflection) Image based Virtual machine hosted Integrated (with development environment) Optimized for development speed over processing speed
6	What is Smalltalk: Commercial Implementations
7	What is Smalltalk: Free Implementations Squeak GNU Smalltalk #Smalltalk Pocket Smalltalk Little Smalltalk S# for AOS
8	Hands on: Dolphin Smalltalk Language Exercises Environment Applications
9	Dolphin Smalltalk: Language Syntax Literal objects integer: 3 character: $a string: ‘string’ symbol: # array: #(1 2 3) comment: “comment” block: [ ] Messages Unary Binary = vs. == Keyword Statements Terminated with period. ^ := cascades Blocks niladic: [ ] value monadic: [ ] value: dyadic: [ ] value:value: Control flow ifTrue: [ ]. ifFalse: [ ]. ifTrue: [ ] ifFalse: [ ]. [ ] whileTrue. [ ] whileTrue: [ ]. [ ] whileFalse. [ ] whileFalse: [ ]. do: [ ]. [ ] repeat. timesRepeat: [ ]. no switch Exceptions [ ] on:do: [ ]. Order of evaluation LR on demand (UBK?)
10	Dolphin Smalltalk: Language Semantics Methods are public Can be flagged as private, but not enforced Variables are protected Require accessors for non-subclass access Uninitialized variables are set to nil Methods return a single value using ^ or implicitly return self Blocks return the value of the last expression Case follows conventions Uppercase first letter for classes Lowercase first letter for variables and methods Camelcase thereafter
11	Dolphin Smalltalk: Language Variables Intrinsic self super thisContext Block Method Arguments Instance Class Class instance Pool (Namespace) Global true false nil Classes
12	Dolphin Smalltalk: Language Structure Statement Method Category Protocol Class Package (Parcel) (Namespace) Application
13	Dolphin Smalltalk: Exercises Control flow before:do: after:do: beside:do // C# code (imagine dot product of vectors) string[] books=new string[]{ "Book1","Book2","Book3" }; string[] authors=new string[]{ "Author1","Author2","Author3" }; for (int i=0;i<books.Length;i++) Console.WriteLine("Book: {0} Author: {1}", books[i],authors[i]);
14	Dolphin Smalltalk: Exercises FizzBuzz Free code Method Class Application
15	Dolphin Smalltalk: Environment Windows Workspace Object playground Transcript stdout Debugger Test-first development Allows code changes during execution Inspector
16	Dolphin Smalltalk: Environment Browsers Classes Packages Protocols Resources Pool Dictionaries Source
17	Dolphin Smalltalk: Environment Files .img Image .sml Source .chg Changes .pac, .pak Packages .st Code *.cls Class
18	Dolphin Smalltalk: Environment Tools Prepackaged SUnit Refactoring support ActiveX/COM ADO and ODBC Contributed DSDN (documentation and newsgroup archives) Chunk browser Profiler
19	Dolphin Smalltalk: Applications Spelling MutsunParser (detector) SpellChecker (corrector) GUI ReadSmartOptions (example GUI) Development MyPackageBrowser Export to RTF or package script, metrics, diagrams MyClassBrowser Export or view as RTF, metrics, edit definition, browse variables Games Equation game
20	Conclusion: Resources Books Web sites Newsgroups
21	Resources: Books The Art and Science of Smalltalk, Simon Lewis Smalltalk Best Practice Patterns, Kent Beck Smalltalk with Style, Suzanne Skublics et al. The Design Patterns Smalltalk Companion, Sherman R. Alpert, et al. The Dolphin Smalltalk Companion, Ted Bracht Squeak: Object-Oriented Design with Multimedia Applications, Murk Guzdial
22	Resources: More books Smalltalk, Objects, and Design, Chamond Liu Smalltalk 80: The Language, Adele Goldberg Object-Oriented Implementation of Numerical Methods: An Introduction with Java & Smalltalk, Didier Besset Kent Beck’s Guide to Better Smalltalk: A Sorted Collection, Kent Beck Squeak: A Quick Trip to ObjectLand, Gene Korienek
23	Resources: Web sites Why Smalltalk? www.whysmalltalk.com Smalltalk Industry Council www.stig.org Smalltalk.org www.smalltalk.org Vendors’ web sites My web site (for slides and code) http://www.keithalcock.com
24	Resources: Newsgroups General comp.lang.smalltalk comp.lang.smalltalk.dolphin comp.lang.smalltalk.advocacy news.totallyobjects.com comp.lang.smalltalk.mt comp.lang.smalltalk.objectstudio news.software.ibm.com ibm.software.vasmalltalk