フリー問題

問題文

A uniform supplier has four reuse requirements: keep callers unchanged as new carrier implementations are added, share common behavior between implementations that differ in one step, let an administrator register a new implementation without a code change, and let another package call in. Which set of techniques matches them?

選択肢

1. An interface for the stable callers, an abstract class for the shared behavior, a configuration record plus resolving the class by name for the registration, and the common callable interface for the cross-package call.
2. An interface for all four, because every one of the four requirements is ultimately about calling something without knowing its concrete type.
3. An abstract class for the stable callers, an interface for the shared behavior, resolving the class by name for the registration, and a platform event for the cross-package call, so each of the four requirements is answered by one construct.
4. An interface for the stable callers, an abstract class for the shared behavior, a configuration record plus resolving the class by name for the registration, and a global class with public methods for the cross-package call, because declaring the class and its methods as visible outside the package is what lets another package compile against it.