A Simple Python Stopwatch

2.0.1 · active · verified Fri Apr 17

stopwatch-py is a lightweight Python library providing a simple stopwatch functionality to measure elapsed time. It is currently at version 2.0.1 and has a low release cadence, primarily focusing on minor improvements and maintenance.

Common errors

```
AttributeError: 'NoneType' object has no attribute 'duration'
```
cause Attempting to chain methods like `s.stop().duration` after upgrading to v2.0.0+. Methods `start()`, `stop()`, `reset()`, `restart()` no longer return `self`.

fix Separate the method calls: `s.stop(); print(s.duration)`.
```
SyntaxError: invalid syntax (often pointing to type hints) or ModuleNotFoundError: No module named 'stopwatch'
```
cause Running `stopwatch-py` v2.0.0+ on Python versions older than 3.5, which do not support the introduced type hints.

fix Upgrade your Python interpreter to version 3.5 or newer, or downgrade the library to `pip install stopwatch-py==1.x`.
```
ImportError: cannot import name 'Stopwatch' from 'stopwatch.stopwatch' (.../stopwatch/stopwatch.py)
```
cause Attempting to import `Stopwatch` from a submodule path (`stopwatch.stopwatch`) which was used in earlier versions. As of v2.0.1, it's a single-file module.

fix Update your import statement to `from stopwatch import Stopwatch`.

Warnings

breaking Methods `start()`, `stop()`, `reset()`, `restart()` no longer return `self`. This change in v2.0.0 breaks method chaining.
Fix: Separate method calls. Instead of `s.stop().duration`, use `s.stop(); print(s.duration)`.
breaking The minimum required Python version increased from Python 3.0 to Python 3.5 due to the introduction of type hints in v2.0.0.
Fix: Ensure your Python environment is 3.5 or newer. If you must use an older Python version, pin `stopwatch-py<2.0.0`.
gotcha The internal `__github__` constant was removed in v2.0.1. While this was not intended to break user code, any specific reliance on this internal constant will now fail.
Fix: Remove any references to `stopwatch.__github__` from your code.

Install

pip install stopwatch-py Install latest version

Imports

Stopwatch
wrong:
```
from stopwatch.stopwatch import Stopwatch
```
correct:
```
from stopwatch import Stopwatch
```
As of v2.0.1, the library was refactored into a single-file module, removing the submodule structure.

Quickstart

Initializes a stopwatch, measures time, stops and resumes, then resets it.

from stopwatch import Stopwatch
import time

s = Stopwatch() # Starts automatically on creation
print(f"Stopwatch started. Elapsed: {s.duration:.2f}s")

time.sleep(1.5)
print(f"After 1.5s, Elapsed: {s.duration:.2f}s")

s.stop()
print(f"Stopwatch stopped. Elapsed: {s.duration:.2f}s")

time.sleep(0.5)
print(f"After 0.5s while stopped, Elapsed: {s.duration:.2f}s (should be same)")

s.start() # Resume
time.sleep(0.75)
print(f"After resuming for 0.75s, Total Elapsed: {s.duration:.2f}s")

s.reset() # Reset to 0 and stop
print(f"Stopwatch reset. Elapsed: {s.duration:.2f}s")

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