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default.py
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32 lines (21 loc) · 850 Bytes
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from typing import Any, TypeVar
class _DefaultPlaceholder:
"""
You shouldn't use this class directly.
It's used internally to recognize when a default value has been overwritten, even
if the overridden default value was truthy.
"""
def __init__(self, value: Any):
self.value = value
def __bool__(self) -> bool:
return bool(self.value)
def __eq__(self, o: object) -> bool:
return isinstance(o, _DefaultPlaceholder) and o.value == self.value
_TDefaultType = TypeVar("_TDefaultType")
def Default(value: _TDefaultType) -> _TDefaultType:
"""
You shouldn't use this function directly.
It's used internally to recognize when a default value has been overwritten, even
if the overridden default value was truthy.
"""
return _DefaultPlaceholder(value) # type: ignore