SOFTWARE DESIGN
DESIGN PATTERNS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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HAS-A can be better than IS-A.
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IS-A can be better than HAS-A.
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Do not use abstract classes.
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The number of classes should be identical with the number of interfaces.
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Detailed explanation-1: -Prefer composition over inheritance as it is more malleable / easy to modify later, but do not use a compose-always approach. With composition, it’s easy to change behavior on the fly with Dependency Injection / Setters. Inheritance is more rigid as most languages do not allow you to derive from more than one type.
Detailed explanation-2: -Inheritance offers a way to reuse code by extending a class easily and with little effort. It is a valuable tool for establishing relationships between classes. In situations where you want to use an object as a field within another class, you should use composition.
Detailed explanation-3: -To favor composition over inheritance is a design principle that gives the design higher flexibility. It is more natural to build business-domain classes out of various components than trying to find commonality between them and creating a family tree.
Detailed explanation-4: -Inheritance and composition are two programming techniques developers use to establish relationships between classes and objects. Whereas inheritance derives one class from another, composition defines a class as the sum of its parts.