python-telegram-bot/telegram/_utils/enum.py

#!/usr/bin/env python
#
# A library that provides a Python interface to the Telegram Bot API
# Copyright (C) 2015-2022
# Leandro Toledo de Souza <devs@python-telegram-bot.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser Public License for more details.
#
# You should have received a copy of the GNU Lesser Public License
# along with this program.  If not, see [http://www.gnu.org/licenses/].
"""This module contains helper functions related to enums.

Warning:
    Contents of this module are intended to be used internally by the library and *not* by the
    user. Changes to this module are not considered breaking changes and may not be documented in
    the changelog.
"""
from enum import Enum
from typing import TypeVar, Union, Type

_A = TypeVar('_A')
_B = TypeVar('_B')
_Enum = TypeVar('_Enum', bound=Enum)


def get_member(enum: Type[_Enum], value: _A, default: _B) -> Union[_Enum, _A, _B]:
    """Tries to call ``enum(value)`` to convert the value into an enumeration member.
    If that fails, the ``default`` is returned.
    """
    try:
        return enum(value)
    except ValueError:
        return default


class StringEnum(str, Enum):
    """Helper class for string enums where the value is not important to be displayed on
    stringification.
    """

    __slots__ = ()

    def __repr__(self) -> str:
        return f'<{self.__class__.__name__}.{self.name}>'