Free Low-level design lessonsLow-level design · Stage 0 · The approach · Step 2
Relationships and diagrams
Association, aggregation, composition, inheritance and dependency, how to draw them, and how a sequence diagram shows a flow. About 13 minutes.
Which test best distinguishes composition from aggregation?
- ACan the part exist without the whole? If not, it is composition
- BIs there more than one part?
- CIs the field public?
Show the answer
Can the part exist without the whole? If not, it is composition. Lifetime ownership is the difference.
4 questions on this idea
Short questions that apply the idea to new cases: trace it, work out a number, put steps in order. A wrong answer explains itself.
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