如何在Python中获取类属性列表（） _列表

【如何在Python中获取类属性列表（）】类是用户定义的蓝图或原型, 从中可以创建对象。类提供了一种将数据和功能捆绑在一起的方法。创建新类将创建一种新的对象类型, 从而允许创建该类型的新实例。每个类实例可以具有附加的属性以维护其状态。类实例还可以具有用于修改其状态的方法(由其类定义)。
例子：

# Python program to demonstrate # classesclass Student:# class variable stream = "COE"# Constructor def __init__( self , name, roll_no):self .name = name self .roll_no = roll_no# Driver's code a = Student( "Shivam" , 3425 ) b = Student( "Sachin" , 3624 )print (a.stream) print (b.stream) print (a.name) print (b.name)# Class variables can be accessed # using class name also print (Student.stream)

输出：

COE COE Shivam Sachin COE

注意：有关更多信息, 请参阅Python类和对象.
获取类属性列表了解我们正在使用的属性很重要。对于小数据, 很容易记住属性名称, 但是在处理海量数据时, 很难记住所有属性。幸运的是, 我们在Python中有一些功能可用于此任务。
方法1：为了获得所有属性, 方法以及类的一些继承的魔术方法的列表, 我们使用了一个内置的dir().
例子：

class Number :# Class Attributes one = 'first' two = 'second' three = 'third'def __init__( self , attr): self .attr = attrdef show( self ): print ( self .one, self .two, self .three, self .attr)n = Number( 2 ) n.show()# Passing both the object # and class asargument # to the dir method print ( '\nBy passing object of class' ) print ( dir (n))print ( '\nBy passing class itself ' ) print ( dir (Number))

输出：

first second third 2通过传递类[‘ __class __’ , ‘ __ delattr __’ , ‘ __ dict __’ , ‘ __ dir __’ , ‘ __ doc __’ , ‘ __ eq __’ , ‘ __ format __’ , ‘ __ ge __’ , ‘ __ getattribute __’ , ‘ __ gt__’ , ‘ __hash __’ , ‘ __ init __’ , ‘ __ init_subclass __’ , ‘ __ le __’ , ‘ __ lt __’ , ‘ __ module __’ , ‘ __ ne __’ , ‘ __ new __’ , ‘ __ reduce __’ , ‘ __ reduce_ex __’ , ‘ __ repr __’ , ‘ __ setattr __’ , ‘ __ sizeof__’ ‘ , ‘ __ str __’ , ‘ __ subclasshook __’ , ‘ __ weakref __’ , ‘ attr’ , ‘ one’ , ‘ show’ , ‘ 3’ , ‘ two’ ]通过传递类本身[‘ __class __’ , ‘ __ delattr __’ , ‘ __ dict__’ , ‘ __ dir __’ , ‘ __ doc __’ , ‘ __ eq __’ , ‘ __ format __’ , ‘ __ ge __’ , ‘ __ getattribute __’ , ‘ __ gt __’ , ‘ __ hash __’ , ‘ __ init __’ , ‘ __ init_subclass __’ , ‘ __ le __’ , ‘ __ lt__’ , ‘ __module __’ , ‘ __ ne __’ , ‘ __ new __’ , ‘ __ reduce __’ , ‘ __ reduce_ex __’ , ‘ __ repr __’ , ‘ __ setattr __’ , ‘ __ sizeof __’ , ‘ __ str __’ , ‘ __ subclasshook ____, ‘ __ weakref __’ , ‘ one’ , ‘ show’ , “ 三个” , “ 两个” ]

方法2：查找属性列表的另一种方法是使用模块检查。该模块提供了一种称为getmemebers()返回类属性和方法的列表。
示例1：

import inspectclass Number :# Class Attributes one = 'first' two = 'second' three = 'third'def __init__( self , attr): self .attr = attrdef show( self ): print ( self .one, self .two, self .three, self .attr)# Driver's code n = Number( 2 ) n.show()# getmembers() returns all the # members of an object for i in inspect.getmembers(n):# to remove private and protected # functions if not i[ 0 ].startswith( '_' ):# To remove other methods that # doesnot start with a underscore if not inspect.ismethod(i[ 1 ]): print (i)

输出：

first second third 2 ('attr', 2) ('one', 'first') ('three', 'third') ('two', 'second')

方法3：要查找属性, 我们也可以使用魔术方法__dict__。此方法仅返回实例属性。
例子：

class Number :# Class Attributes one = 'first' two = 'second' three = 'third'def __init__( self , attr): self .attr = attrdef show( self ): print ( self .one, self .two, self .three, self .attr)# Driver's code n = Number( 2 ) n.show()# using __dict__ to access attributes # of the object n along with their values print (n.__dict__)# to only access attributes print (n.__dict__.keys())# to only access values print (n.__dict__.values())

输出如下：