« Back to Design Patterns in Object-Oriented Programming

USING DESIGN PATTERNS

---

Contents:

• How design patterns solve design problems
• How to select a design pattern

---

Key reference: DPG4

---

How design patterns solve design problems

• Identifying the appropriate objects for the purpose
• Determining object granularity
• Specifying object interfaces
• Specifying object implementations
  NOTE: An object’s implementation is defined by its class
• Using reuse mechanisms
  • Class inheritance
  • Object composition
• Relating run-time and compile-time structures
  • Object aggregation
  • Object acquaintance
• Making the design adaptible to change
  • Role of design patterns in apps, toolkits and frameworks

Reference: DGP4 (p. 41-68)

How to select a design pattern

• Consider how design patterns solve design problems
• Scan the “intent” sections
• Study how patterns interrelate
• Study patterns of similar purposes
• Examine cause of redesign (see DPG4, p. 61)
• Consider what should be variable in your design
  • This is the opposite of examining cause of redesign
  • Consider what you want to be able to change without redesign

Reference: DPG4 (p. 68-69)