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
除了这些答案之外,我还将包括一个函数(python 3),用于输出任何值的几乎整个结构。它使用dir来建立属性名的完整列表,然后对每个名称使用getattr。它会显示值的每个成员的类型,如果可能的话还会显示整个成员:
import json
def get_info(obj):
type_name = type(obj).__name__
print('Value is of type {}!'.format(type_name))
prop_names = dir(obj)
for prop_name in prop_names:
prop_val = getattr(obj, prop_name)
prop_val_type_name = type(prop_val).__name__
print('{} has property "{}" of type "{}"'.format(type_name, prop_name, prop_val_type_name))
try:
val_as_str = json.dumps([ prop_val ], indent=2)[1:-1]
print(' Here\'s the {} value: {}'.format(prop_name, val_as_str))
except:
pass
现在,以下任何一项都应该让你有所了解:
get_info(None)
get_info('hello')
import numpy
get_info(numpy)
# ... etc.
其他回答
检查模块:
inspect模块提供了几个有用的函数来帮助获取 有关活动对象的信息,如模块、类、方法、 函数、回溯、帧对象和代码对象。
使用getmembers()可以看到类的所有属性及其值。要排除私有或受保护的属性,请使用. startwith('_')。要排除方法或函数,请使用inspect.ismethod()或inspect.isfunction()。
import inspect
class NewClass(object):
def __init__(self, number):
self.multi = int(number) * 2
self.str = str(number)
def func_1(self):
pass
inst = NewClass(2)
for i in inspect.getmembers(inst):
# Ignores anything starting with underscore
# (that is, private and protected attributes)
if not i[0].startswith('_'):
# Ignores methods
if not inspect.ismethod(i[1]):
print(i)
注意,ismethod()用于i的第二个元素,因为第一个元素只是一个字符串(它的名字)。
跑题:类名使用CamelCase。
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
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)
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.
dir(instance)
# or (same value)
instance.__dir__()
# or
instance.__dict__
然后可以用type()测试类型是什么,或者用callable()测试是否为方法。