Week 1

Question 1

Name this: formalized best practices can be used to solve
common problems when designing an application
or system. General & reusable.

Answer 1

Patterns

Question 2

T/F - Patterns are a finished design that can be transformed into code

Answer 2

False

Question 3

Patterns are a description or recipe for how to _____ a _______

Answer 3

solve a problem

Question 4

What are 5 advantages of patterns?

Answer 4

1. General, not tied to a specific problem
2. Flexible
3. Faster (proven, well understood)
4. Easier to read/understand the code if you know the pattern
5. Fosters communication among programmers (they don’t have to include a diagram if you both know)

Question 5

What are 3 disadvantages of patterns?

Answer 5

1. They have to be programmed fresh for each application
2. Can complicate designs and impact performance
3. Must know when to use them (and how)

Question 6

Indirection, when used in patterns results in both an advantage and disadvantage

Answer 6

Indirection is used to be flexible, but can complicate designs and impact performance

Question 7

What are the 3 groups of design patterns?

Answer 7

Creative, Structural, Behavioural

Question 8

What is the focus of the creative DP?

Answer 8

Class instantiation

Question 9

What is the focus of the structural DP?

Answer 9

Class composition

Question 10

What is the focus of the behavioural dp?

Answer 10

Communication among objects

Question 11

Name this creative DP: Restricts object creation for a class to only one instance.

Answer 11

Singleton

Question 12

Name this creative DP: constructs complex objects by separating construction and
representation.

Answer 12

Builder

Question 13

Name this creative DP: Creates objects without specifying the exact class to create.

Answer 13

Factory

Question 14

Name this Structural DP: Match interfaces of different classes

Answer 14

Adapter

Question 15

Name this Behavioural DP: Register with an object and get notified of changes

Answer 15

Observer

Question 16

Name this Behavioural DP: Encapsulate a command request as an object

Answer 16

Command

Question 17

Creative DPs pneumonic device

Answer 17

SOBFAP

Question 18

Behavioural DP pneumonic device

Answer 18

SOCISI or ISICOS

Question 19

Name 4 criticisms of design patterns

Answer 19

1. Leads to ineffective solutions (Solution may be found but it’s not necessary/worse)
2. “New” patterns are created which are already existing techniques
3. No formal foundation (just opinions of the GoF)
4. Focusing on pattern not code (could be eliminated with more abstraciton)

Question 20

T/F - Anti-patterns criticize DP’s and suggest not to use them

Answer 20

False, they build on the DP concept.

Question 21

These provide ways of dealing with frequent “pattern failure” encountered by the authors

Answer 21

Anti-patterns

Question 22

Anti-patterns describe repeated patterns that appear to be… BUT the negative….

Answer 22

appear to be beneficial, BUT the negative consequences out-weigh the possible advantages