27 Jan 2003

1
Visitor

• 27 Jan 2003
• Lecture 11

2
Outline

• Previous Business
• HW1 now available via my.wpi.edu
• Lecture Contents
• Iterator Design Pattern
• Visitor Design Pattern
• New Business
• Java AWT help session Monday 700 PM (FL 311)
• Java Help Sessions Tuesday 500 700 (Annex)
• Regular TA office hours still valid

3
Iterator

• Access all elements of an aggregate without
  revealing its internal structure
• Whiteboard

Element elements new Element 10 for (int i
0 i lt 10 i ) Element e
elementsi
4
Visitor Motivation

• Set example without Visitor
• Discussion

5
Visitor Design Pattern

• Abstract base Visitor class
• Double dispatch
• Better encapsulation
• Analysis

6
Tuesday Assignments

• Review design patterns
• singleton, iterator, visitor
• Prepare for Midterm
• HW2 due on Thursday

7
References

• Visitor
• College Freshman Study Behavior