Exam Quick Reference

Note:

• The intention of this guide is to be succinct. Don't use this for extended explanation, just note brief points. People can follow links for explanation.
• Don't be too specific. This is not a Cheat Sheet with direct answers from last year or whatever. It's a concise list of concepts to jog your memory.
• If you are Wal, bear in mind that just because it's mentioned on this page, doesn't mean it would be wrong to ask questions on it in the exam! It might be better not to read this so as to remain a disinterested party.

Contradictory Design Maxims

• Design by contract and Tell, don't ask
• Composite pattern and Avoid no-op overrides

Design Pattern Cliff Notes

• Decorator
  • Identify by: Both HAS A and IS A at the same time, with multiple subclasses.
  • Used for: Adding flexible combinations of specialized functionality.
  • Classic Example: Adding scrolling functionality, borders, etc to a window.
  • Why better than alternatives: Avoids combinatorial explosion of subclasses.

• Composite
  • Identify by: Both HAS A and IS A at the same time, usually without subclasses.
  • Used for: Making many act as one.
  • Classic Example: Making a shape comprising other shapes.
  • Why better than alternatives: Can use singular and collective instances totally transparently (identically).