单例设计模式

class Singleton(object):

    def __new__(cls, *args, **kwargs):
        if not hasattr(cls, '_the_instance'):
            cls._the_instance = object.__new__(cls, *args, **kwargs)
        return cls._the_instance


class A(Singleton):

    def __init__(self):
        print('i am __init__')

a = A()
b = A()
print(id(a))
print(id(b))

i am __init__
i am __init__
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