What are some examples of command patterns in programming?

What are some examples of command patterns in programming?

The command pattern is a behavioral design pattern that turns a request into a stand-alone object. This allows for parameterization of clients with queues, requests, and operations. Some examples include: 1. Undo/Redo functionality in applications. 2. Menu systems in GUI applications. 3. Task scheduling in background processes.

Can you explain how the undo/redo functionality works using the command pattern?

Sure! In the undo/redo functionality, each action is encapsulated as a command object. When an action is performed, the command is executed and stored in a stack. For undo, the command is popped from the stack and its 'undo' method is called. For redo, the command is moved to a redo stack and its 'execute' method is called again.

What programming languages support the command pattern?

Most object-oriented programming languages support the command pattern, including Java, C#, Python, and C++. They allow you to create classes and objects that can encapsulate commands.

Can you give me a code example of the command pattern?

Certainly! Here's a simple example in Python:

class Command:
    def execute(self):
        pass

class LightOnCommand(Command):
    def __init__(self, light):
        self.light = light
    
    def execute(self):
        self.light.turn_on()

class Light:
    def turn_on(self):
        print('The light is on!')

light = Light()
light_on = LightOnCommand(light)
light_on.execute()  # Output: The light is on!