37 lines
943 B
Python
37 lines
943 B
Python
from __future__ import annotations
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import enum
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import typing as t
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class Sentinel(enum.Enum):
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"""Enum used to define sentinel values.
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.. seealso::
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`PEP 661 - Sentinel Values <https://peps.python.org/pep-0661/>`_.
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"""
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UNSET = object()
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FLAG_NEEDS_VALUE = object()
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def __repr__(self) -> str:
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return f"{self.__class__.__name__}.{self.name}"
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UNSET = Sentinel.UNSET
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"""Sentinel used to indicate that a value is not set."""
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FLAG_NEEDS_VALUE = Sentinel.FLAG_NEEDS_VALUE
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"""Sentinel used to indicate an option was passed as a flag without a
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value but is not a flag option.
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``Option.consume_value`` uses this to prompt or use the ``flag_value``.
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"""
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T_UNSET = t.Literal[UNSET] # type: ignore[valid-type]
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"""Type hint for the :data:`UNSET` sentinel value."""
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T_FLAG_NEEDS_VALUE = t.Literal[FLAG_NEEDS_VALUE] # type: ignore[valid-type]
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"""Type hint for the :data:`FLAG_NEEDS_VALUE` sentinel value."""
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