Timing context manager in Python

Context managers guarantee cleanup; this one measures elapsed time.

import time
from contextlib import contextmanager

@contextmanager
def timed(label):
    start = time.perf_counter()
    try:
        yield
    finally:
        elapsed = time.perf_counter() - start
        print(f"{label}: {elapsed:.3f}s")

How it works

1. @contextmanager turns the generator into a with-block helper.
2. Code before the yield runs on entry, recording the start time.
3. The finally block always prints the elapsed time on exit.

Keywords and builtins used here

• def
• finally
• print
• timed
• try
• yield

The run, in numbers

Lines

11

Characters to type

204

Tokens

50

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 29 seconds.

Type this snippet

Step 2 of 5 in Protocols & context managers, step 16 of 53 in Pythonic Python.

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