静态方法
类方法
属性方法
通过@staticmethod装饰器即可把其装饰的方法变为一个静态方法,什么是静态方法呢?其实不难理解,普通的方法,可以在实例化后直接调用,并且在方法里可以通过self.调用实例变量或类变量,但静态方法是不可以访问实例变量或类变量的,一个不能访问实例变量和类变量的方法,其实相当于跟类本身已经没什么关系了,它与类唯一的关联就是需要通过类名来调用这个方法
类方法通过@classmethod装饰器实现,类方法和普通方法的区别是, 类方法只能访问类变量,不能访问实例变量
属性方法的作用就是通过@property把一个方法变成一个静态属性
#-*- encoding:utf8 -*-
#Wind clear raise class Dog(): member = 0 def __init__(self, name):
self.name = name
def walk(self):
print("walk function") @staticmethod # 无法通过self访问属性、方法
def talk(self):
#self.walk()
print("Talk now is: ", self.name) class Animal(object):
name = "类变量"
def __init__(self, name):
self.name = name @classmethod # 设置方法只能访问类变量,无法访问类属性
def talk(self):
print("The Animal talk:", self.name) class Person(object):
def __init__(self, name):
self.name = name
@property # 将一个方法设置为属性
def eat(self): # 无法通过Person.eat()调用
print(self.name, "is eating")
return "hel" d = Dog("DD")
#d.talk("aaaaa") #AttributeError: 'str' object has no attribute 'name'
d.talk(d) a = Animal("Dark")
a.talk() p = Person("Fengqingyang")
s = p.eat
print("return [%s]" % s)
Talk now is: DD
The Animal talk: 类变量
Fengqingyang is eating
return [hel]
二、特殊属性及成员
__doc__ __class__ __module__ __dict__
class Dog():
"""Dog doc content"""
###
#-*- encoding:utf8 -*-
#Wind clear raise from 类的特殊属性方法_2 import Dog class Foo(object):
"""doc内容"""
def __init__(self, name):
self.name = name def __call__(self, *args, **kwargs):
print("__call__:", args, kwargs) f = Foo("Wind")
print(Foo.__doc__)
print(f.__class__, f.__module__)
d = Dog()
print(d.__module__, d.__class__)
print(d.__doc__)
f("hello", name="test")
#Foo("")("call", age=333)
print(Foo.__dict__) # 类的所有属性成员
print(f.__dict__) # 实例的所有属性成员
f.name = "dict测试"
print(Foo.__dict__) # 结果内容不变
print(f.__dict__) # 实例内容name变更
“”“
/Library/Frameworks/Python.framework/Versions/3.5/bin/python3.5 /data/youngboy/youngboy/study/day07/类的特殊属性方法.py
doc内容
<class '__main__.Foo'> __main__
类的特殊属性方法_2 <class '类的特殊属性方法_2.Dog'>
Dog doc content
__call__: ('hello',) {'name': 'test'}
{'__init__': <function Foo.__init__ at 0x1021df378>, '__module__': '__main__', '__call__': <function Foo.__call__ at 0x1021df400>, '__dict__': <attribute '__dict__' of 'Foo' objects>, '__doc__': 'doc内容', '__weakref__': <attribute '__weakref__' of 'Foo' objects>}
{'name': 'Wind'}
{'__init__': <function Foo.__init__ at 0x1021df378>, '__module__': '__main__', '__call__': <function Foo.__call__ at 0x1021df400>, '__dict__': <attribute '__dict__' of 'Foo' objects>, '__doc__': 'doc内容', '__weakref__': <attribute '__weakref__' of 'Foo' objects>}
{'name': 'dict测试'} Process finished with exit code 0 ”“”
2、__str__、__getitem__、__setitem__ __delitem__
class Dog():
"""Dog doc content"""
def __init__(self, name):
self.name = name def __str__(self): ##print(d)
return "Wind"
def test(self):
pass
def __getitem__(self, item): # 调用时触发
print("getitem: ", item)
def __setitem__(self, key, value):
print("setitem: ", key, value) # 设置时触发
def __delitem__(self, key): # 删除时触发
print("del:", key) d = Dog("Dog")
print(d) result = d["k"] # 触发 __getitem__
d["k"] = "setkey" # 触发 __setitem
del d["k"] # 触发__delitem__
"""
Wind
getitem: k
setitem: k setkey
del: k
"""
类的另类定义:
def func(self):
print("hello Wind ", self.name, self.age) def __init__(self,name, age):
self.name = name
self.age = age # 利用逼格定义类, 同时也说明python一切皆对象
Foo = type('Foo2', (object,), {'talk': func, '__init__': __init__})
# 类名 type(object_or_name, bases, dict) f = Foo("Wind", 33)
f.talk() print(type(f))
print(type(Foo))
hello Wind Wind 33
<class '__main__.Foo2'>
<class 'type'>
类的生成 调用 顺序依次是 __new__ --> __call__ --> __init__
class Foo(object):
def __init__(self):
print("init") def __call__(self, *args, **kwargs):
print("hello call") def __new__(cls, *args, **kwargs):
print("hello new")
return object.__new__(cls) # 去继承父类的__new__方法
# 类似 F.__init__(self) f = Foo()
hello new
init
__new__ 在实例化之前干点什么事
class Foo(object):
def __init__(self, name):
self.name = name
print("init") def __call__(self, *args, **kwargs):
print("hello call") def __new__(cls, *args, **kwargs):
print("hello new")
# return object.__new__(cls) # 去继承父类的__new__方法
# 类似 F.__init__(self) f = Foo()
print(type(f)) 程序结果 f 没有真正的创建,so,在init之前运行了new
<class 'NoneType'>
反射
class Foo(object):
def walk(self):
print("walk") def talk(msg=""):
print("hello talk") s = input(">>").strip()
obj =Foo() if hasattr(obj, s):
v = getattr(obj, s)
v() else:
setattr(obj, s, talk)
v = getattr(obj, s)
v() print(dir(obj)) '''
>>input_str
hello talk
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'input_str', 'walk'] '''
异常:
a = []
s = {}
s[1] = "hello" try:
# a[3]
# b
# c = 1
# s[2]
open("aaa")
except (IndexError, KeyError) as e: # 多个异常写在一起
print("异常 ", e)
except NameError as e: # 单个异常
print("异常", e)
except Exception as e:
print("各种异常:", e)
else: # 无异常
print("无异常")
finally: # 最终
print("无论有无异常、表示感谢") class MyException(BaseException): # 自定义异常
def __init__(self, msg):
self.msg = msg # 重载父类 __str__, 父类默认直接 return self.msg
# def __str__(self):
# print("str....") # 先输出 str... 然后输出msg
# return self.msg try:
raise MyException("我的异常") # 直接抛出异常
except MyException as e: #
print("自定义: ", e)