是否有一种方法可以获取类实例上存在的属性列表?
class new_class():
def __init__(self, number):
self.multi = int(number) * 2
self.str = str(number)
a = new_class(2)
print(', '.join(a.SOMETHING))
期望的结果是输出"multi, str"。我希望它能看到脚本各个部分的当前属性。
是否有一种方法可以获取类实例上存在的属性列表?
class new_class():
def __init__(self, number):
self.multi = int(number) * 2
self.str = str(number)
a = new_class(2)
print(', '.join(a.SOMETHING))
期望的结果是输出"multi, str"。我希望它能看到脚本各个部分的当前属性。
当前回答
请参见以下Python shell脚本执行顺序,它将给出从创建类到提取实例字段名的解决方案。
>>> class Details:
... def __init__(self,name,age):
... self.name=name
... self.age =age
... def show_details(self):
... if self.name:
... print "Name : ",self.name
... else:
... print "Name : ","_"
... if self.age:
... if self.age>0:
... print "Age : ",self.age
... else:
... print "Age can't be -ve"
... else:
... print "Age : ","_"
...
>>> my_details = Details("Rishikesh",24)
>>>
>>> print my_details
<__main__.Details instance at 0x10e2e77e8>
>>>
>>> print my_details.name
Rishikesh
>>> print my_details.age
24
>>>
>>> my_details.show_details()
Name : Rishikesh
Age : 24
>>>
>>> person1 = Details("",34)
>>> person1.name
''
>>> person1.age
34
>>> person1.show_details
<bound method Details.show_details of <__main__.Details instance at 0x10e2e7758>>
>>>
>>> person1.show_details()
Name : _
Age : 34
>>>
>>> person2 = Details("Rob Pike",0)
>>> person2.name
'Rob Pike'
>>>
>>> person2.age
0
>>>
>>> person2.show_details()
Name : Rob Pike
Age : _
>>>
>>> person3 = Details("Rob Pike",-45)
>>>
>>> person3.name
'Rob Pike'
>>>
>>> person3.age
-45
>>>
>>> person3.show_details()
Name : Rob Pike
Age can't be -ve
>>>
>>> person3.__dict__
{'age': -45, 'name': 'Rob Pike'}
>>>
>>> person3.__dict__.keys()
['age', 'name']
>>>
>>> person3.__dict__.values()
[-45, 'Rob Pike']
>>>
其他回答
你要这个干什么?如果不知道你的确切意图,可能很难得到最好的答案。
It is almost always better to do this manually if you want to display an instance of your class in a specific way. This will include exactly what you want and not include what you don't want, and the order will be predictable. If you are looking for a way to display the content of a class, manually format the attributes you care about and provide this as the __str__ or __repr__ method for your class. If you want to learn about what methods and such exist for an object to understand how it works, use help. help(a) will show you a formatted output about the object's class based on its docstrings. dir exists for programatically getting all the attributes of an object. (Accessing __dict__ does something I would group as the same but that I wouldn't use myself.) However, this may not include things you want and it may include things you do not want. It is unreliable and people think they want it a lot more often than they do. On a somewhat orthogonal note, there is very little support for Python 3 at the current time. If you are interested in writing real software you are going to want third-party stuff like numpy, lxml, Twisted, PIL, or any number of web frameworks that do not yet support Python 3 and do not have plans to any time too soon. The differences between 2.6 and the 3.x branch are small, but the difference in library support is huge.
获取对象的属性
class new_class():
def __init__(self, number):
self.multi = int(number) * 2
self.str = str(number)
new_object = new_class(2)
print(dir(new_object)) #total list attributes of new_object
attr_value = new_object.__dict__
print(attr_value) #Dictionary of attribute and value for new_class
for attr in attr_value: #attributes on new_class
print(attr)
输出
['__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__', 'multi', 'str']
{'multi': 4, 'str': '2'}
multi
str
__attrs__给出了一个实例的属性列表。
>>> import requests
>>> r=requests.get('http://www.google.com')
>>> r.__attrs__
['_content', 'status_code', 'headers', 'url', 'history', 'encoding', 'reason', 'cookies', 'elapsed', 'request']
>>> r.url
'http://www.google.com/'
>>>
你可以使用dir(your_object)来获取属性,使用getattr(your_object, your_object_attr)来获取值
用法:
for att in dir(your_object):
print (att, getattr(your_object,att))
如果你的对象没有__dict__,这特别有用。如果不是这样,你也可以尝试var(your_object)
attributes_list = [attribute for attribute in dir(obj) if attribute[0].islower()]