# coding=utf-8
#
# This file is part of Hypothesis (https://github.com/DRMacIver/hypothesis)
#
# Most of this work is copyright (C) 2013-2015 David R. MacIver
# (david@drmaciver.com), but it contains contributions by others. See
# https://github.com/DRMacIver/hypothesis/blob/master/CONTRIBUTING.rst for a
# full list of people who may hold copyright, and consult the git log if you
# need to determine who owns an individual contribution.
#
# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at http://mozilla.org/MPL/2.0/.
#
# END HEADER

from __future__ import division, print_function, absolute_import

import threading
from contextlib import contextmanager


class DynamicVariable(object):

    def __init__(self, default):
        self.default = default
        self.data = threading.local()

    @property
    def value(self):
        return getattr(self.data, 'value', self.default)

    @value.setter
    def value(self, value):
        setattr(self.data, 'value', value)

    @contextmanager
    def with_value(self, value):
        old_value = self.value
        try:
            self.data.value = value
            yield
        finally:
            self.data.value = old_value
