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For each pair, say whether you would use inheritance (is a) or composition (has a), and why…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each pair, say whether you would use inheritance (is a) or composition (has a), and why.
TeacherandPersonLibraryandBookCircleandShapePhoneandBatteryStackandlist
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Say the sentence aloud, both ways, and keep the one that sounds right.
- A teacher is a person. Inheritance.
- A library has books. Composition.
- A circle is a shape. Inheritance.
- A phone has a battery. Composition.
- A stack is a list? Not really: a stack allows only push and pop, and a list allows much more. It is better for a stack to have a list inside, and to offer only the stack operations. Composition.
Check. The last one is a famous case. If the child allows things that the parent allows but the idea forbids, "is a" is false.
Answer: inheritance, composition, inheritance, composition, composition.
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