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
>>> ', '.join(i for i in dir(a) if not i.startswith('__'))
'multi, str'
这当然会打印类定义中的任何方法或属性。你可以通过将i.startwith('__')更改为i.startwith('_')来排除“私有”方法。
其他回答
>>> ', '.join(i for i in dir(a) if not i.startswith('__'))
'multi, str'
这当然会打印类定义中的任何方法或属性。你可以通过将i.startwith('__')更改为i.startwith('_')来排除“私有”方法。
请参阅已按顺序执行的python shell脚本,在这里您将获得以逗号分隔的字符串格式的类属性。
>>> class new_class():
... def __init__(self, number):
... self.multi = int(number)*2
... self.str = str(number)
...
>>> a = new_class(4)
>>> ",".join(a.__dict__.keys())
'str,multi'<br/>
我使用的是python 3.4
上面所有的答案都是正确的,你有三个选项可以选择
dir () vars () __dict__
>>> dir(a)
['__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']
>>> vars(a)
{'multi': 4, 'str': '2'}
>>> a.__dict__
{'multi': 4, 'str': '2'}
>>> class new_class():
... def __init__(self, number):
... self.multi = int(number) * 2
... self.str = str(number)
...
>>> a = new_class(2)
>>> a.__dict__
{'multi': 4, 'str': '2'}
>>> a.__dict__.keys()
dict_keys(['multi', 'str'])
您可能还会发现pprint有帮助。
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.