How to use context managers (with statement) in Python

Question

I see "with" statements used in Python. What are context managers and how do I create my own?

devops_guru · Accepted Answer

Using context managers
# File handling (automatic close)
with open('file.txt', 'r') as f:
    content = f.read()

# Multiple context managers
with open('input.txt', 'r') as fin, open('output.txt', 'w') as fout:
    fout.write(fin.read())
Creating custom context manager
from contextlib import contextmanager

@contextmanager
def timer():
    import time
    start = time.time()
    yield
    end = time.time()
    print(f"Elapsed: {end - start:.2f}s")

# Usage
with timer():
    # code to time
    time.sleep(1)

How to use context managers (with statement) in Python

1 Answer

Using context managers

Creating custom context manager

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