36 lines
731 B
Python
36 lines
731 B
Python
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"""
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元类 - 设计模式 - 单例模式(让一个类只能创建唯一的实例)
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"""
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class SingletonMeta(type):
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"""单例类的元类(描述其他类的类)"""
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def __init__(cls, *args, **kwargs):
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cls.__instance = None
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def __call__(cls, *args, **kwargs):
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if cls.__instance is None:
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cls.__instance = super().__call__(*args, **kwargs)
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return cls.__instance
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class President(metaclass=SingletonMeta):
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"""总统(单例类)"""
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def __init__(self, name):
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self.name = name
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def main():
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p1 = President("王大锤")
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p2 = President("奥巴马")
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print(p1.name)
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print(p2.name)
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print(p1 == p2)
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print(p1 is p2)
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if __name__ == '__main__':
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main()
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