If public methods are virtual in an API, which rule is not being followed?

If public methods are virtual in an API, which rule is not being followed?

• A. Public methods should not be virtual
• B. G21 Fail fast; don't fail silently
• C. G11 Pay attention to edge cases
• D. G24 Overload with care

Answer: (A)

When public methods are designed to be virtual in an API, the principle that "public methods should not be virtual" is not being adhered to. This guideline often stems from the concept that exposing virtual methods can lead to a number of issues in API usage and behavior. Virtual methods allow for overriding in derived classes, which can create unexpected behaviors when the API is used in implementation-oriented ways. Clients of the API may rely on specific behaviors of the public methods, and virtuality introduces the risk of breakage if derived classes alter those behaviors. This can lead to difficulties in understanding the contract provided by the API, resulting in a less predictable and more fragile interface. Additionally, virtual methods can complicate versioning and make it harder to manage backward compatibility when the base class evolves. Overall, designing public methods as non-virtual upholds a simpler and more reliable contract for the API consumers, promoting stability and predictability in API interactions.

When public methods are designed to be virtual in an API, the principle that "public methods should not be virtual" is not being adhered to. This guideline often stems from the concept that exposing virtual methods can lead to a number of issues in API usage and behavior.

Virtual methods allow for overriding in derived classes, which can create unexpected behaviors when the API is used in implementation-oriented ways. Clients of the API may rely on specific behaviors of the public methods, and virtuality introduces the risk of breakage if derived classes alter those behaviors. This can lead to difficulties in understanding the contract provided by the API, resulting in a less predictable and more fragile interface.

Additionally, virtual methods can complicate versioning and make it harder to manage backward compatibility when the base class evolves. Overall, designing public methods as non-virtual upholds a simpler and more reliable contract for the API consumers, promoting stability and predictability in API interactions.