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49. Using Context Managers

1. Introduction​

Context managers handle setup and cleanup automatically. The most common use is file handling with with.

2. Basic Example​

with open("example.txt", "r") as f:
    data = f.read()
print("File closed?", f.closed)

3. Custom Context Managers​

Create your own with a class implementing __enter__ and __exit__.

class MyResource:
    def __enter__(self):
        print("Resource acquired")
        return self
    def __exit__(self, exc_type, exc_val, exc_tb):
        print("Resource released")

with MyResource() as r:
    print("Using resource")

4. Contextlib Module​

Simplify creation with contextlib.

from contextlib import contextmanager

@contextmanager
def simple_manager():
    print("Start")
    yield
    print("End")

with simple_manager():
    print("Inside block")

5. Benefits​

  • Automatic cleanup
  • Cleaner code
  • Error safety

6. Next Steps​

✅ You now understand context managers.
Next: Handling exceptions.