2. Introduction to Smalltalk

• Administrivia:
• EVERYONE NEEDS A COC ACCOUNT!!
• Why Classes?
• Templates or factories for objects
• Objects as robots
• Messages and methods
• Object differentiation
• --> Inheritance
• Why Design?
• Because OOP is hard
• Structure of the Browser
• Categories to organize classes
• Categories to organize methods: Protocols
• Same protocol in multiple classes
• More than one method per message
• Smalltalk file structure
• Image
• VM
• Changes file
• Sources file
• Smalltalk Literals
• Numbers, characters, strings, literal arrays
• Special symbols
• self, super
• true, false nil
• Naming
• locals are lowercase
• Globals are UpperCase
• Messages
• unary
• 7 negated
• 'a b c' printString
• binary
• 3 * 4
• Keyword
• aDict at: 'fred' put: 'student'
• Precedence
• parentheses precede everything
• unary, then binary, then keyword -- all left-to-right
• The Power of the Smalltalk Environment
• Your First Classes: Muppet, FriendlyMuppet, GrouchyMuppet
• Creating classes
• Instance variables
• Instance methods
• Finding things out
• Explain
• implementors of
• senders of
• Filing in and out
• Inspecting and Debugging