Key Relationships

• Adapter - Bridge* - Composite - Decorator - Facade - Flyweight* - Proxy
  These patterns are classified as structural design patterns. [GoF, p10]
  
  • Adapter provides an alternative interface for an (already existing) class or object.
  • Bridge* lets an abstraction and its implementation vary independently.
  • Composite composes (already existing) objects into a tree structure.
  • Decorator provides additional functionality for an (already existing) object.
  • Facade provides an unified interface for (already existing) objects in a subsystem.
  • Flyweight* supports large numbers of fine-grained objects efficiently.
  • Proxy provides additional functionality when accessing an (already existing) object.
• Composite - Builder - Iterator - Visitor - Interpreter
  • Composite provides a way to represent a part-whole hierarchy
    as a tree (composite) object structure.
  • Builder provides a way to create the elements of an object structure.
  • Iterator provides a way to traverse the elements of an object structure.
  • Visitor provides a way to define new operations for the elements of an object structure.
  • Interpreter represents a sentence in a simple language
    as a tree (composite) object structure (abstract syntax tree).
• Composite - Flyweight
  • Composite and Flyweight often work together.
    Leaf objects can be implemented as shared flyweight objects.
• Composite - Chain of Responsibility
  • Composite and Chain of Responsibility often work together.
    Existing composite object structures can be used to define the successor chain.