Command and Iterator Patterns

The Command Pattern is a behavioral design pattern that turns a request into a stand-alone object. This object contains all information about the request, including the method to call and the parameters it needs.

Think of it like putting an instruction into a package. You can then pass this package around, queue it, or even undo it later, without the sender needing to know how the instruction is carried out.

To understand the Command Pattern, let's look at its key players:

• Command: An interface or abstract class declaring an execute() method.
• ConcreteCommand: Implements the Command interface, binding a specific Receiver object to an action.
• Receiver: The object that performs the actual work. It knows how to carry out the operation.
• Invoker: Asks the command to carry out its request. It doesn't know the specifics of the operation or the receiver.
• Client: Creates a ConcreteCommand object and sets its Receiver.