27 lines
584 B
Python
27 lines
584 B
Python
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import functools
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from typing import Any, MutableMapping, Type
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class Singleton(type):
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_instances: MutableMapping[Type[Any], Any] = {}
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def __call__(cls, *args, **kwargs):
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if cls not in cls._instances:
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cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
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return cls._instances[cls]
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def memoized_property(fgetter):
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stored = []
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@functools.wraps(fgetter)
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def wrapped(self):
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nonlocal stored
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if not stored:
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stored.append(fgetter(self))
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return stored[0]
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return property(wrapped)
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