#!/usr/bin/env python3
# © Copyright 2021-2023, Scott Gasch
"""A simple stopwatch decorator / context for timing things. This was factored out
of decorator utils so that bootstrap.py can keep its imports lighter."""
import contextlib
import time
from typing import Callable, Literal
[docs]class Timer(contextlib.AbstractContextManager):
"""
A stopwatch to time how long something takes (walltime).
Example usage::
with stopwatch.Timer() as t:
do_the_thing()
walltime = t()
print(f'That took {walltime} seconds.')
"""
def __init__(self) -> None:
self.start = 0.0
self.end = 0.0
def __enter__(self) -> Callable[[], float]:
"""Returns a functor that, when called, returns the walltime of the
operation in seconds.
"""
self.start = time.perf_counter()
self.end = 0.0
return lambda: self.end - self.start
def __exit__(self, *args) -> Literal[False]:
self.end = time.perf_counter()
return False