COMP2007-Design patterns

Question 0

Gamma, Helm, Johnson, Vlissides
Gang of four
23 patterns

Answer 0

Defined by

• pattern name
• problem/usage
• solution
• consequences

Intent
Aka
Motivation
Applicability
Structure
Participants
Collaborations
Consequences
Implementation techniques
Known uses
Related patterns

Question 1

Design patterns

Answer 1

Tried and tested solutions for recurring problems in programming

Good patterns

• be as general as poss
• proven solution

You must know

• problem you’re facing
• know design patterns
• understand relationships btwn classes and how to allocate responsibilities to them

Question 2

Patterns are classified into

Answer 2

Creational - concerned with object construction and the installation process

Structural - concerned with composition of classes/objects: how classes and objects are composed to form larger structures

Behavioural - concerned with the way classes and objects interact/patterns of communication between classes

Question 3

Interface

Answer 3

Set of methods (and variables) that one class allows other classes to access

A CLASS i n t e r f a c e speaking abstractly is the collection of methods and fields that the class permits other classes to access.

A class implements a given interface by means of the code in its methods

Interface defined by what it does, not how its implemented

Question 4

Structural patterns

Answer 4

1. Adapter
2. Bridge
3. Composite
4. Decorator
5. Facade
6. Flyweight
7. Proxy

Question 5

Creational patterns

Answer 5

1. Factory method
2. Abstract factory
3. Builder
4. Prototype
5. Singleton

Question 6

Behavioural patterns

Answer 6

1. Chain of responsibility
2. Command
3. Interpreter
4. Iterator
5. Mediator
6. Memento
7. Observer
8. State
9. Strategy
10. Template method
11. Visitor