面向对象高级小结 - 好文

目录

* 一、面向对象高级小结 <https://www.cnblogs.com/nickchen121/p/11070460.html#一面向对象高级小结>
* 1.1 isinstance,issubclass
<https://www.cnblogs.com/nickchen121/p/11070460.html#isinstanceissubclass>
* 1.2 反射 <https://www.cnblogs.com/nickchen121/p/11070460.html#反射>
* 1.3 call <https://www.cnblogs.com/nickchen121/p/11070460.html#call>
* 1.4 new <https://www.cnblogs.com/nickchen121/p/11070460.html#new>
* 1.5 元类 <https://www.cnblogs.com/nickchen121/p/11070460.html#元类>
* 二、单例模式 <https://www.cnblogs.com/nickchen121/p/11070460.html#二单例模式>
* 2.0.1 利用类的绑定方法的特性
<https://www.cnblogs.com/nickchen121/p/11070460.html#利用类的绑定方法的特性>
* 2.0.2 利用装饰器 <https://www.cnblogs.com/nickchen121/p/11070460.html#利用装饰器>
* 2.0.3 利用元类(正宗的)
<https://www.cnblogs.com/nickchen121/p/11070460.html#利用元类正宗的>
一、面向对象高级小结

1.1 isinstance,issubclass

isinstance判断是否为类的实例化对象,会检测父类,而type不会检测父类

issubclass,判断是否为其子类

1.2 反射

* hasattr:通过字符串判断是否类属性存在
* getattr:通过字符串获取类属性
* setattr:通过字符串修改类属性
* delattr:通过字符串删除类属性
1.3 call
class Foo: def __init__(self): print('Foo()会触发我') def __call__(self):
print('Foo()()/f()会触发我') f = Foo() f()
1.4 new
class Foo: def __new__(self): print('new') obj = object.__new__(self) return
obj def __init__(self): print('init') f = Foo()
1.5 元类

元类用来造类的

元类()-->类-->init

元类()()-->对象--->call

类分为几部分:类名/类体名称空间/父类们
class Mymeta(type): def __init__(self,class_name,class_bases,class_dic): #
控制类的逻辑代码 super().__init__(class_name,class_bases,class_dic) def
__call__(self,*args,**kwargs): # 控制类实例化的参数 obj = self.__new__(self) #
obj就是实例化的对象 self.__init__(obj,*args,**kwargs) print(obj.__dict__) # 控制类实例化的逻辑
return obj class People(metaclass=Mymeta): def __init__(self,name,age):
self.name = name self.age = age
二、单例模式

2.0.1 利用类的绑定方法的特性
NAME = 'nick' AGE = 18 class People(): __instance = None @classmethod def
from_conf(cls): if cls.__instance: return cls.__instance cls.__instance =
cls(NAME,AGE) return cls.__instance
People.from_conf()

People.from_conf()

2.0.2 利用装饰器
NAME = 'nick' AGE = 18 def deco(cls): cls.__instance = cls(NAME,AGE) def
wrapper(*args,**kwargs): if len(args) == 0 and len(kwargs) == 0: return
cls.__instance res = cls(*args,**kwargs) return res return wrapper @deco class
People(): def __init__(self,name,age): self.name = name self.age = age
peo1 = People()

peo2 = People()

2.0.3 利用元类(正宗的)
NAME = 'nick' AGE = 18 class Mymeta(type): def
__init__(self,class_name,class_bases,class_dict):
super().__init__(class_name,class_bases,class_dict) self.__instance =
self(NAME,AGE) def __call__(self,*args,**kwargs): if len(args) == 0 and
len(kwargs) == 0: return self.__instance obj = object.__new__(self)
self.__init__(obj,*args,**kwargs) return obj class People(metaclass=Mymeta):
def __init__(self,name,age): self.name = name self.age = age peo1 = People()
peo2 = People()

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