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本文實例為大家分享了python單例模式的具體代碼，供大家參考，具體內容如下
多次實例化的結果指向同一個實例
單例模式實現方式
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文件里內容:
import settings
class MySQL:
print('run...')
def __init__(self, ip, port):
self.ip = ip
self.port = port
instance = MySQL(settings.IP, settings.PORT)
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持億速云。
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