contextvars_with_contextmanager.py

# Copyright 2020 Google LLC.
# SPDX-License-Identifier: Apache-2.0

from contextvars import ContextVar
from contextlib import contextmanager

# library code

my_option = ContextVar('my_option', default='default')

@contextmanager
def my_option_context(value):
  token = my_option.set(value)
  yield
  my_option.reset(token)

# example usage

assert my_option.get() == 'default'

my_option.set('new')
assert my_option.get() == 'new'

with my_option_context('temporary'):
  assert my_option.get() == 'temporary'

assert my_option.get() == 'new'