Master Context Managers (Beyond with open())

You've used with open() a million times. But did you know you can create your own context managers? They're perfect for resource management (files, locks, connections).

The Classic Way (Using a Class):

class ManagedFile:
    def __init__(self, filename):
        self.filename = filename

    def __enter__(self):
        self.file = open(self.filename, 'w')
        return self.file

    def __exit__(self, exc_type, exc_val, exc_tb):
        if self.file:
            self.file.close()

# Usage
with ManagedFile('hello.txt') as f:
    f.write('Hello, context manager! 👋')

The Elegant Way (Using contextlib):

For simpler cases, use @contextmanager to turn a generator into a context manager.

from contextlib import contextmanager

@contextmanager
def managed_file(filename):
    try:
        f = open(filename, 'w')
        yield f  # This is where the 'with' block runs
    finally:
        f.close()  # This ensures cleanup

# Usage is identical!
with managed_file('hello2.txt') as f:
    f.write('Even cleaner! 🧼')

Why? This ensures resources are always cleaned up, even if an error occurs. It's the Pythonic way to handle setup/teardown.