Can you change the access modifier of a base class method in a derived class? (Hiding vs Overriding)
Access Modifiers, Overriding and Hiding
Generally, a derived class cannot override a base method with a more restrictive access level because that would violate substitutability. For example, a public base method cannot normally become protected or private in an override. Languages have specific rules around increasing visibility, method hiding and overriding. Hiding creates a new member in the derived class rather than participating in runtime polymorphism, so it should be used deliberately and not as a substitute for proper overriding.
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An override normally preserves the accessibility contract of the base method.
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Reducing visibility would prevent valid base-type usage.
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Overriding participates in polymorphic dispatch.
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Hiding/shadowing creates a separate member in the derived type.
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Exact access-modifier rules vary between languages.
Follow-up Questions
- What is method hiding?
- What is runtime polymorphism?
- Why can't an override reduce visibility?
- How does C# new keyword differ from override?