python 17 lines · 5 steps

A reusable timing context manager in Python

Wrap any block in a with-statement to measure its wall-clock time and report it automatically.

Explained by highlit

Intermediate context-manager timing generators resource-cleanup

1import time
2from contextlib import contextmanager
3 
4 
5@contextmanager
6def timer(label="elapsed", logger=None):
7    start = time.perf_counter()
8    result = {"seconds": None}
9    try:
10        yield result
11    finally:
12        result["seconds"] = time.perf_counter() - start
13        message = f"{label}: {result['seconds'] * 1000:.2f}ms"
14        if logger is not None:
15            logger.info(message)
16        else:
17            print(message)

01 / 01

STEP 01

Walkthrough

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Three takeaways

1The @contextmanager decorator turns a single-yield generator into a full with-block protocol.
2Putting cleanup in a finally clause guarantees timing runs even when the wrapped code raises.
3Yielding a mutable object lets the caller read results the manager fills in after the block ends.

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