22 lines
740 B
Python
22 lines
740 B
Python
"""Simple singleton meta-class definition"""
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from abc import ABCMeta as AbstractBaseMetaClass
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from typing import Dict
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class Singleton(AbstractBaseMetaClass):
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"""
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Taken from : <https://stackoverflow.com/q/6760685/10599709>
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This meta-class allows us to declare `Configuration` as a singleton.
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This way, we are able to import `Configuration` in multiple modules, ...
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... whereas it is effectively loaded only once.
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You cannot instantiate this meta-class directly.
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"""
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_instances: Dict["Singleton", object] = {}
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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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