Detailed design

Question 1

How do the slides draw the boundary between architecture and detailed design?

Answer 1

Architecture fixes non-local, intensional structures that span the system; detailed design refines those structures locally so each component can be built and tested. :contentReference[oaicite:26]{index=26}

Question 2

State the Intensionality–Locality Thesis in one sentence.

Answer 2

Architectural specs are intensional and non-local; implementation is extensional and local; detailed design is intensional but local—bridging between the two. :contentReference[oaicite:27]{index=27}

Question 3

List the three “3-1-2” object-oriented principles highlighted in the lecture.

Answer 3

(3) Encapsulate what varies (1) Program to an interface, not an implementation (2) Favour composition over inheritance. :contentReference[oaicite:28]{index=28}

Question 4

What does “encapsulate what varies” mean in practice?

Answer 4

Place changeable behaviour behind a stable interface so modifications don’t ripple through the rest of the code. :contentReference[oaicite:29]{index=29}

Question 5

Why is “program to an interface” a safeguard for modifiability?

Answer 5

Clients depend on abstractions, allowing alternative implementations or mocks without code surgery. :contentReference[oaicite:30]{index=30}

Question 6

Give one reason to favour composition over inheritance.

Answer 6

Composition assembles behaviour at run-time, avoiding rigid class hierarchies and the fragile-base-class problem. :contentReference[oaicite:31]{index=31}

Question 7

In design-model terminology, what is the difference between intensional and extensional views?

Answer 7

Intensional views describe families of structures with free variables; extensional views list concrete instances (actual classes, methods). :contentReference[oaicite:32]{index=32}

Question 8

Define a “design model” according to the lecture.

Answer 8

A small logical structure whose atoms are classes, methods, and relations such as Extends or Invoke—abstract enough to reason about yet close to code. :contentReference[oaicite:33]{index=33}

Question 9

Why are design patterns considered intensional and local?

Answer 9

They describe reusable collaboration templates (intensional) that apply within a component boundary (local), not across the whole architecture. :contentReference[oaicite:34]{index=34}

Question 10

Describe the Decorator pattern in one line.

Answer 10

Wrap an object to add responsibilities dynamically without changing its code or class hierarchy. :contentReference[oaicite:35]{index=35}

Question 11

What problem does the Adapter pattern solve?

Answer 11

It converts the interface of an existing class or library into one that a client expects, isolating vendor APIs. :contentReference[oaicite:36]{index=36}

Question 12

How does Builder differ from Abstract Factory?

Answer 12

Builder separates construction steps from representation, letting the same process create different products; Abstract Factory simply chooses among product families. :contentReference[oaicite:37]{index=37}

Question 13

Give one benefit of the Decorator pattern for modifiability.

Answer 13

New behaviour layers can be added or removed at run-time without editing existing source code. :contentReference[oaicite:38]{index=38}

Question 14

Outline the process view of detailed design given in the slides.

Answer 14

Revisit ASRs → apply 3-1-2 to hotspots → document class/sequence diagrams → feed uncertainties into the architectural backlog or prototypes. :contentReference[oaicite:39]{index=39}

Question 15

How does the architectural backlog interact with detailed design?

Answer 15

Design-time questions or spikes are logged so unresolved issues stay visible and are prioritised alongside feature work. :contentReference[oaicite:40]{index=40}

Question 16

Why can detailed design decisions make or break performance?

Answer 16

Choosing inefficient data structures or over-deep inheritance can negate architectural performance tactics. :contentReference[oaicite:41]{index=41}

Question 17

What is an extensional artefact example for a Java system?

Answer 17

A concrete UML class diagram listing every class, method, and field. :contentReference[oaicite:42]{index=42}

Question 18

How does a design model map onto code specifications?

Answer 18

The model’s abstractions (classes, relations) are instantiated as language-specific constructs (e.g., Java interfaces, imports) before implementation. :contentReference[oaicite:43]{index=43}

Question 19

According to Eden & Kazman, why is detailed design still intensional?

Answer 19

It captures families of local solutions (patterns, rules) that are applied repeatedly, not one-off concrete instances. :contentReference[oaicite:44]{index=44}

Question 20

Provide an example of applying 3-1-2 in the Twitter scenario from the slides.

Answer 20

Encapsulate varying timeline algorithms, define a TimelineStrategy interface, and inject concrete strategy objects rather than subclassing Twitter. :contentReference[oaicite:45]{index=45}

Question 21

How can design patterns enhance testability?

Answer 21

Interfaces and composition (Strategy, Adapter) allow dependency injection and mocking, enabling isolated unit tests. :contentReference[oaicite:46]{index=46}

Question 22

Distinguish between an architectural tactic and a design pattern.

Answer 22

Tactic addresses a quality attribute at system level (e.g., caching for performance); design pattern organises object collaboration locally inside a component. :contentReference[oaicite:47]{index=47}

Question 23

What is the first step when refactoring legacy code without tests, per Feathers?

Answer 23

Identify change points and test points, then break dependencies so that tests can be inserted. (Slides quote Feathers in legacy context.) :contentReference[oaicite:48]{index=48}

Question 24

Why can inheritance harm modifiability in large code-bases?

Answer 24

Child classes inherit internal details; changing a base class risks ripple effects and fragile subclasses. :contentReference[oaicite:49]{index=49}

Question 25

State a concise exam definition of detailed design.

Answer 25

The phase that refines architectural structures locally, using principles and patterns so each component can be constructed, tested, and evolved. :contentReference[oaicite:50]{index=50}