Future Pattern Design Pattern Lesson

The Future Pattern is a design pattern that addresses the need for managing asynchronous operations in a clean and efficient way. It allows you to handle the results of asynchronous operations without blocking the main thread of execution.

• Asynchronous Operations: Tasks that run independently of the main program flow.
• Future Object: A placeholder for a result that is initially unknown but will be available later.
• Promise: An object representing the eventual completion (or failure) of an asynchronous operation.

To implement the Future Pattern, follow these steps:

1. Create a Future class that contains a private variable to hold the result and a status flag.
2. Implement methods to set the result and check the status.
3. Use the Future object in your asynchronous operations to return the result when it becomes available.

When using the Future Pattern, consider the following best practices:

• Always handle exceptions within asynchronous operations to avoid unhandled rejections.
• Use Futures in combination with Promises to create a robust asynchronous workflow.
• Document your Future methods to clarify their asynchronous nature.

Here’s a simple implementation of the Future Pattern in Python:

import threading
import time

class Future:
    def __init__(self):
        self.result = None
        self.completed = False
        self.lock = threading.Lock()

    def set_result(self, value):
        with self.lock:
            self.result = value
            self.completed = True

    def get_result(self):
        with self.lock:
            if not self.completed:
                raise Exception("Result not available yet")
            return self.result

def async_task(future):
    time.sleep(2)
    future.set_result("Task Complete")

# Usage
future = Future()
thread = threading.Thread(target=async_task, args=(future,))
thread.start()

# Main flow continues
print("Waiting for the task to complete...")
time.sleep(1)
print(future.get_result())