Command design pattern

What is the Command Design Pattern?

The Command Design Pattern is a behavioral design pattern that encapsulates a request as an object, thereby allowing for parameterization of clients, queuing of requests, and logging of operations. It decouples the
sender (invoker) and receiver (executor) of the command, providing flexibility in designing systems.

When to Use the Command Design Pattern?

• Undo/Redo functionality: Useful when you need to support undoable operations, such as in text editors or graphical applications.
• Macro commands: When multiple commands should be executed together (batch processing).
• Decoupling request from execution: When the requester of an operation should not be tightly coupled to its execution logic.
• Queueing requests: Useful in multi-threaded applications or task scheduling.
• Logging changes: If changes should be stored for auditing or replay.

Real-World Analogy of the Command Pattern

Imagine a restaurant:

1. A customer places an order (Invoker).
2. The waiter takes the order and passes it to the kitchen (Command Object).
3. The chef prepares the meal (Receiver).
4. The waiter serves the dish to the customer.

Here, the waiter is an intermediary that decouples the customer from the chef. The order can also be modified, canceled, or queued, demonstrating the flexibility of the command pattern.

Key Takeaways

• Encapsulates requests as objects, allowing flexibility in command execution.
• Supports undo/redo functionality by maintaining a history of commands.
• Decouples invoker from receiver, making the system more modular and extensible.
• Useful in GUI applications, job queues, and remote control systems.

Would you like an example with command queuing or macro commands? 🚀