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8ac5b3e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | from __future__ import annotations
import enum
import typing as t
class Sentinel(enum.Enum):
"""Enum used to define sentinel values.
.. seealso::
`PEP 661 - Sentinel Values <https://peps.python.org/pep-0661/>`_.
"""
UNSET = object()
FLAG_NEEDS_VALUE = object()
def __repr__(self) -> str:
return f"{self.__class__.__name__}.{self.name}"
UNSET = Sentinel.UNSET
"""Sentinel used to indicate that a value is not set."""
FLAG_NEEDS_VALUE = Sentinel.FLAG_NEEDS_VALUE
"""Sentinel used to indicate an option was passed as a flag without a
value but is not a flag option.
``Option.consume_value`` uses this to prompt or use the ``flag_value``.
"""
T_UNSET = t.Literal[UNSET] # type: ignore[valid-type]
"""Type hint for the :data:`UNSET` sentinel value."""
T_FLAG_NEEDS_VALUE = t.Literal[FLAG_NEEDS_VALUE] # type: ignore[valid-type]
"""Type hint for the :data:`FLAG_NEEDS_VALUE` sentinel value."""
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