python单例模式实例解析_Python

python单例模式实例解析

2021-03-30 00:17屈逸 Python

这篇文章主要为大家详细介绍了python单例模式实例的相关资料，具有一定的参考价值，感兴趣的小伙伴们可以参考一下

本文实例为大家分享了python 单例模式的具体代码，供大家参考，具体内容如下

多次实例化的结果指向同一个实例

单例模式实现方式

方式一:

									import settings

									class MySQL:

									  __instance = None

									  def __init__(self, ip, port):

									    self.ip = ip

									    self.port = port

									  @classmethod

									  def from_conf(cls):

									    if cls.__instance is None:

									      cls.__instance = cls(settings.IP,settings.PORT)

									    return cls.__instance

									obj1 = MySQL.from_conf()

									obj2 = MySQL.from_conf()

									obj3 = MySQL.from_conf()

									print(obj1)

									print(obj2)

									print(obj3)

方式二:

									import settings

									def singleton(cls):

									  _instance = cls(settings.IP, settings.PORT)

									  def wrapper(*args, **kwargs):

									    if args or kwargs:

									      obj = cls(*args, **kwargs)

									      return obj

									    return _instance

									  return wrapper

									@singleton

									class MySQL:

									  def __init__(self, ip, port):

									    self.ip = ip

									    self.port = port

									obj1 = MySQL()

									obj2 = MySQL()

									obj3 = MySQL()

									print(obj1)

									print(obj2)

									print(obj3)

方式三:

									import settings

									class Mymeta(type):

									  def __init__(self, class_name, class_bases, class_dic):

									    self.__instance = self(settings.IP, settings.PORT)

									  def __call__(self, *args, **kwargs):

									    if args or kwargs:

									      obj = self.__new__(self)

									      self.__init__(obj, *args, **kwargs)

									      return obj

									    else:

									      return self.__instance

									class MySQL(metaclass=Mymeta):

									  def __init__(self, ip, port):

									    self.ip = ip

									    self.port = port

									obj1 = MySQL()

									obj2 = MySQL()

									obj3 = MySQL()

									print(obj1)

									print(obj2)

									print(obj3)

方式四:

									def f1():

									  from singleton import instance

									  print(instance)

									def f2():

									  from singleton import instance,MySQL

									  print(instance)

									  obj = MySQL('1.1.1.1', '3389')

									  print(obj)

									f1()

									f2()

									singleton.py文件里内容:

									import settings

									class MySQL:

									  print('run...')

									  def __init__(self, ip, port):

									    self.ip = ip

									    self.port = port

									instance = MySQL(settings.IP, settings.PORT)