# 单例模式

class Foo:

    __n = None

    def __init__(self):

        self.name = "nick"

        self.age = 18

        self.job = "pythoner"

    @staticmethod

    def dl():

        if Foo.__n:

            return Foo.__n

        else:

            Foo.__n = Foo()

            return Foo.__n

# 创建对象时不能再直接使用：obj = Foo()，而应该调用特殊的方法：obj = Foo.dl() 。

f1 = Foo.dl()

print(f1)

f2 =Foo.dl()

print(f2)

f3 =Foo.dl()

print(f3)

# 运行结果

<__main__.Foo object at 0x0000000001142390>

<__main__.Foo object at 0x0000000001142390>

<__main__.Foo object at 0x0000000001142390>

def singleton(argv):

    dic = {}

    def s(*args, **kwargs):

        if argv not in dic:

            dic[argv] = argv(*args, **kwargs)

            return dic[argv]

        else:

            return dic[argv]

    return s

# 类上加单例装饰器

@singleton

class Foo:

    pass

@singleton

class Foo2:

    pass