python是一种面向对象的语言，利用类的抽象可以大大提高代码的复用和结构，减少重复造轮子的过程，也让代码变得更加清晰易懂、便于维护。
1.python中的类 Class
python中的类提供了一系列数据和方法的组合，类是python的一种对象，可以由它构建出新的实例。实例包含了类所具有的属性和类中声明的方法。首先来看一个基本类的写法：
class Dog(object):"""This is a dog class as example"""def __init__(self,name):"""This is initial funciton"""self.name = namedef voice(self):"""Dog will speak as wangwang """print('WangWangWang')
这是一个非常简单的类，但其中包含了类很重要的几个部分，包括类的声明、初始化的构造函数、属性、成员方法的定义等。其中有几个地方需要注意：object是python中所有类的基类，在类的初始化时显式继承
self是类里的实例，为实例本身，在初始化后具有一系列的属性和方法,类方法的第一个参数按照约定需要使用self开头。
一个完整的类的声明还会包括基本属性、私有属性和保护变量等内容：
class Dog(object):"""This is a dog class as example"""animal_kind = 'dog' #基本属性animal_legs = 4 #基本属性也建议写到初始化构造函数中去def __init__(self,name,age,params...): #利用__init__(self,params)进行初始化"""This is initial funciton"""self.name = nameself.age = age#还可以定义各种其他的属性，作为实例初始化时候将传进来的参数进行赋值self.__gender = 'male' #两个下划线开头是私有内部属性，只能在类内访问def __privateGender(self):"""This is pravate method"""print('This dog gender is %s',self.__gender)def voice(self):"""Dog will speak as wangwang """print('WangWangWang')print(self.__privateGender(self))def run(self):"""runing with legs"""print("This dog has %d legs to run"%self.animal_legs)#定义一大堆各种各样的方法
class是可以进行继承以及方法重写的，可以基于一个类继承，也可以基于多个类进行多重继承。
class Husky(Dog):"""Husky inherent the Dog attris and method"""def __init__(self,name,age,color,params):Dog.__init__(self, name, age) #利用Dog这个父类的初始化self.color = color #子类中特定属性的初始化def jump(self):"""Husky special jump function"""print('This dog could jump jump')def voice(self):"""重写覆盖父类的函数，实现自己的特殊的方法"print('AoAoAoWu~~~~~~')
2.语言风格规范
为了更好的便于阅读和复用代码，还需要使得代码满足一定的语言风格，这里选用了google的风格规范来对类进行声明，下面是一个例子
# ref from:https://zh-google-styleguide.readthedocs.io/en/latest/google-python-styleguide/python_style_rules/class MyDog(object):"""Summary of class here. #1.首先一句话简短的总结这个类的功能和作，文档字符串需要用三引号包括# 对齐，空一行If the class has public attributes, they may be documented herein an ``Attributes`` section and follow the same formatting as afunction's ``Args`` section. Alternatively, attributes may be documentedinline with the attribute's declaration (see __init__ method below).Properties created with the ``@property`` decorator should be documentedin the property's getter method.Longer class information....#随后详细的说明类的细节Longer class information....#类内部第一行的开始的文字都可以被__doc__# 空一行，开始写这个类的各个属性，包括数据类型和作用Attributes:likes_spam: A boolean indicating if we like SPAM or not. #属性的声明，包括数据类型和作用，xxx类型的数据for/used to/ofxxxeggs: An integer count of the eggs we have laid."""def __init__(self, likes_spam=False):"""Inits SampleClass with blah."""# 下面是详细的例子"""Example of docstring on the __init__ method.# 对于初始化方法的说明The __init__ method may be documented in either the class leveldocstring, or as a docstring on the __init__ method itself.Either form is acceptable, but the two should not be mixed. Choose oneconvention to document the __init__ method and be consistent with it.# 对于初始化方法的一些记录Note:Do not include the `self` parameter in the ``Args`` section.# 初始化的参数输入，对于方法来说参数名(数据类型)：描述的格式来写Args:param1 (str): Description of `param1`.param2 (:obj:`int`, optional): Description of `param2`. Multiplelines are supported.param3 (:obj:`list` of :obj:`str`): Description of `param3`."""self.likes_spam = likes_spamself.eggs = 0# 输入参数的初始化self.attr1 = param1self.attr2 = param2self.attr3 = param3 #: Doc comment *inline* with attribute#: list of str: Doc comment *before* attribute, with type specifiedself.attr4 = ['attr4']self.attr5 = None"""str: Docstring *after* attribute, with type specified."""def public_method(self):"""Performs operation blah.""""""Summary line. #第一行简写函数描述# 空一行，对齐详细描述Extended description of function.# 空一行对齐，写args 的各个内容，变量名（类型）：描述Args:arg1 (int): Description of arg1arg2 (str): Description of arg2# 空一行对齐，不同情况下的if else 返回值（类型）：描述Returns:int/float/bool dtype: Description of return value"""
Example
最后完整的按照风格来写一个类的示例：
class Dog(object):"""This is a class for Dog Dog class is the parents class of all dog, this class contain general attributes of dog and some common function of dogs, such asnum legs, the voice fucntion, the runing functions.Attributes:name: A string of dog's namekind: A string of dog's familyage: A integer of dog yearsgender: A boolean gender of dog, male=1 of famle=0legs A integer if dog's legsweight: A float of dogs weightsize: A string of dogs, one of big, middle, smal"""def __init__(self,args,gender,size):"""initialize dog class, all attributes pass in with args, which is a dict or indepent paramsInput contain dict and str params, also there is private attributeArgs:args.name(str): dog nameargs.kind(str): dog familyargs.age(int) : dog agegender(bool) : dog gender, male=1,famale=0args.weight(float): dog weightsize(str): dog size"""self.name = args.nameself.kind = args.kindself.age = args.ageself.weight = args.weight# __legs(int) : dog legs,privite attribute, not the inputs params,写在前面用#做注释，不属于输入的参数的初始化self.__legs = 4 """写在后面用三引号__legs(int) : dog legs,privite attribute"""self.size = sizeself.gender = genderdef voice(self,size):"""This is dog speak fucntionDifferent dog with different voice which related to the size,age and kindArgs:size(str): dog sizeage(int) : dog agekind(srt): dog kindReturns:None, just print the voice"""if size=='big':print('Big WangWang')elif size =='middle':print('M wang')elif size=='small':print('Miao')# 附注：return 可从任意深度跳出函数，None
ref:
+++ /3/tutorial/classes.html
/blog//06/18/improve-your-python-python-classes-and-object-oriented-programming/
https://zh-google-styleguide.readthedocs.io/en/latest/google-python-styleguide/python_language_rules/
++++https://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html
/python3/python3-class.html 单继承/多继承
/question/27699413
++注意namespace
函数闭包：/question/25950466
