What is Inheritance? What is the 'IS-A' relationship?
Inheritance and the IS-A Relationship
Inheritance is an OOPS mechanism where a derived or child class acquires accessible members and behavior from a base or parent class and can extend or specialize that behavior. An IS-A relationship means the derived type is a valid conceptual specialization of the base type. For example, a SavingsAccount IS-A BankAccount. At a senior engineering level, I use inheritance only when the subtype genuinely satisfies the behavioral contract of the base type, otherwise composition is usually safer.
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Inheritance represents an IS-A relationship.
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The child specializes or extends the behavior of the parent.
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It enables polymorphism through a common base type.
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Inheritance creates coupling between parent and child.
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The Liskov Substitution Principle should be considered before introducing inheritance.
Follow-up Questions
- What is the Liskov Substitution Principle?
- When should inheritance be avoided?
- Can inheritance provide runtime polymorphism?
- What is the difference between inheritance and composition?