What to know for the exam

• Smalltalk will be used for questions, but there will not be questions about the grammar.

• Questions might ask – how particular patterns are different for Smalltalk– How to program a pattern in Smalltalk– How to program basic OO problem– questions that assume general knowledge of basic

classes like collections or streams

Kent Beck patterns

• Composed method• Complete creation method• Conversion method• Query method• Intention revealing message• Double dispatch

Core patterns

• Mediator• Façade• Proxy• Command• Template Method• Adapter• Null Object

• Composite• Strategy• Decorator• State• Iterator• Observer• Value Object

Creational

• Abstract factory (peripheral)• Factory method• Prototype• Builder• Singleton• Dependency Injection

Peripheral

• Memento• Chain of responsibility• Bridge• Visitor• Type Object• Extension Object• Generation Gap

Compound

• Flyweight– To save space, factor out a Value Object, and

create them using a Memoizing Factory that records the flyweight pool.

• Interpreter– Represent a program with a Composite, and let

the class hierarchy match the grammar of the language. Define an “interpret” method in each class.

Dangerous Patterns

• Mediator– Supposed to be used to allow colleagues to be

reusable. Is often used to allow programmers to continue to be procedural.

• Singleton– Supposed to be used to encapsulate global state

when it cannot be eliminated. Is often used as a justification of global state.

Principles

• Single responsibility principle• Open/closed principle• Liskov substitution principle• Dependency inversion principle