52 lines
1.5 KiB
Python
52 lines
1.5 KiB
Python
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from typing import Any, Callable, Optional, Type, Union
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class _ClassProperty:
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def __init__(
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self,
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fget: classmethod,
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fset: Optional[classmethod] = None,
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):
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self.fget = fget
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self.fset = fset
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def __get__(self, obj: Any, klass: Optional[Type] = None) -> Any:
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if klass is None:
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klass = type(obj)
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return self.fget.__get__(obj, klass)()
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def __set__(self, obj: Any, value: Any) -> None:
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if self.fset is None:
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raise AttributeError("Can't set class property (no setter)")
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klass = type(obj)
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return self.fset.__get__(obj, klass)(value)
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def setter(
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self, fset: Union[Callable[[Any, Any], None], classmethod]
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) -> "_ClassProperty":
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"""
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Defines the setter for a class property
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"""
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if not isinstance(fset, classmethod):
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fset = classmethod(fset)
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self.fset = fset
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return self
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def classproperty(fget: Union[Callable[[Any], Any], classmethod]) -> _ClassProperty:
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"""
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Declares a new class property with the decorated getter.
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"""
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if not isinstance(fget, classmethod):
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fget = classmethod(fget)
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return _ClassProperty(fget)
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class _ClassPropertyMeta(type):
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def __setattr__(self, key: str, value: Any) -> None:
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obj = getattr(self, key, None)
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if isinstance(obj, _ClassProperty):
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return obj.__set__(self, value)
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return super().__setattr__(key, value)
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