Which statement describes the Command pattern?

Which statement describes the Command pattern?

• A. Involves direct method calls between components.
• B. Is about data persistence.
• C. Encapsulates a request as an object with execute and undo; decouples sender and receiver.
• D. Is primarily about lazy initialization.

Answer: (C)

The Command pattern is about turning a request into a stand-alone object that can be passed around, stored, or undone. This object usually provides an execute method, and often an undo method, which allows the same command to be invoked by different parts of a system without those parts needing to know how the action is carried out. Because the sender of the command only interacts with the command object and not with the receiver, the two are decoupled, making it easy to queue commands, log them, or implement undo/redo functionality. The statement highlighting encapsulating a request as an object with execute and undo, while decoupling sender and receiver, captures this idea precisely. The other descriptions describe different ideas—direct method calls imply tight coupling, data persistence focuses on storage, and lazy initialization targets performance optimization—not the command pattern.

The Command pattern is about turning a request into a stand-alone object that can be passed around, stored, or undone. This object usually provides an execute method, and often an undo method, which allows the same command to be invoked by different parts of a system without those parts needing to know how the action is carried out. Because the sender of the command only interacts with the command object and not with the receiver, the two are decoupled, making it easy to queue commands, log them, or implement undo/redo functionality. The statement highlighting encapsulating a request as an object with execute and undo, while decoupling sender and receiver, captures this idea precisely. The other descriptions describe different ideas—direct method calls imply tight coupling, data persistence focuses on storage, and lazy initialization targets performance optimization—not the command pattern.