Object-Oriented Design

Overall View

Object-oriented design is focused on identifying objects and operations. Here's a high-level view of the process:

I personally start by parsing the statement of the problem (from its original form as a paragraph of English) into nouns and verbs, eliminating redundancies, and creating a mapping between nouns and data structures and verbs and transformations of data structures.

- Paul Fisher   (ap-compsci, 8/98)

Identifying Objects (and Classes)

• Identify the nouns (objects) in the problem description.
• Identify more objects in your developing problem solution. (Design is incremental and iterative!   --   Grady Booch)
• From these objects, determine what new types (classes) you need.
  Example: BlackJack Program
  • cards
  • a deck
  • a dealer
  • player(s)

  Sample Design Questions:

  • Do different cards represent different types? Or are suit and rank attributes of a single card type?
  • Are the dealer and player instances of the same class? I.e., objects of the same type?
  • Should there be a separate Hand class?