数据结构｜单例类

class Test:
    pass

a=Test()
print(id(a))
b=Test()
print(id(b))

-------------------------------------------------------------------------------

返回

1169738445096

1169739284664

class Sinleton(object):

    _judge = None  # 定义一个类属性用于判断

    def __new__(cls):



        if cls._judge==None:

            #如果—_judge为空，则是第一次创建实例

            #那就通过父类的_new_(cls)创建

            cls._judge=object.__new__(cls)

            return  cls._judge

        else:

            #不是第一次创建，返回上一个对象的引用

            return cls._judge



obj1=Sinleton()

obj2=Sinleton()

print(id(obj1))

print(id(obj2))

返回

2212148678952

2212148678952  #相同引用地址

class Sinleton(object):

    pass

k=Sinleton()

from Singletons import k as obj1

print(id(obj1))

from Singletons import k as obj2

print(id(obj2))

#返回引用地址易相同