CPSA Software Design Principles 5

Question 1

Which design principle is MOST directly related to the concept of an 'anti-corruption layer' in domain-driven design?

Accepted Answer

Separation of Concerns

Answer

An anti-corruption layer separates different domain models or contexts, directly embodying Separation of Concerns by isolating external system concerns from internal domain logic.

Question 2

When evaluating software design, 'afferent coupling' (Ca) measures:

Accepted Answer

The number of packages that depend on a given package

Answer

Afferent coupling (Ca) counts the number of external packages that depend on a given package, indicating how responsible that package is to others.

Question 3

A module has high efferent coupling (Ce). What risk does this MOST indicate?

Accepted Answer

This module is unstable because changes in dependencies can force changes here

Answer

High efferent coupling means a module depends on many others; if any of those dependencies change, this module may also need to change, making it unstable.

Question 4

Which metric is computed as I = Ce / (Ca + Ce) and indicates the instability of a software package?

Accepted Answer

Instability (I)

Answer

Robert Martin's Instability metric I = Ce / (Ca + Ce) ranges from 0 (maximally stable) to 1 (maximally unstable), measuring a package's resilience to change.

Question 5

What does the 'Stable Dependencies Principle' prescribe about the direction of dependency between packages?

Accepted Answer

Packages should depend in the direction of stability

Answer

The Stable Dependencies Principle states that a package should only depend on packages that are more stable than itself, ensuring stable packages are not forced to change due to unstable dependents.

CPSA Exam Practice Test

CPSA Exam Practice Test

CPSA Software Design Principles 5