将 Python argparse.Namespace() 视为字典的正确方法是什么？
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what is the right way to treat Python argparse.Namespace() as a dictionary?
提问by Jason S
If I want to use the results of argparse.ArgumentParser(), which is a Namespaceobject, with a method that expects a dictionary or mapping-like object (see collections.Mapping), what is the right way to do it?
如果我想将 的结果（argparse.ArgumentParser()它是一个Namespace对象）与一个需要字典或类似映射的对象的方法一起使用（请参阅collections.Mapping），那么正确的方法是什么？
C:\>python
Python 2.7.3 (default, Apr 10 2012, 23:31:26) [MSC v.1500 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
>>> import argparse
>>> args = argparse.Namespace()
>>> args.foo = 1
>>> args.bar = [1,2,3]
>>> args.baz = 'yippee'
>>> args['baz']
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'Namespace' object has no attribute '__getitem__'
>>> dir(args)
['__class__', '__contains__', '__delattr__', '__dict__', '__doc__', '__eq__', '_
_format__', '__getattribute__', '__hash__', '__init__', '__module__', '__ne__',
'__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__
', '__str__', '__subclasshook__', '__weakref__', '_get_args', '_get_kwargs', 'ba
r', 'baz', 'foo']
Is it proper to "reach into" an object and use its __dict__property?
“进入”一个对象并使用它的__dict__属性是否合适？
I would think the answer is no: __dict__smells like a convention for implementation, but not for an interface, the way __getattribute__or __setattr__or __contains__seem to be.
我认为答案是否定的：__dict__闻起来像执行公约，而不是一个接口，方式__getattribute__或__setattr__或__contains__似乎是。
采纳答案by Raymond Hettinger
You can access the namespace's dictionary with vars():
您可以使用vars()访问命名空间的字典：
>>> import argparse
>>> args = argparse.Namespace()
>>> args.foo = 1
>>> args.bar = [1,2,3]
>>> d = vars(args)
>>> d
{'foo': 1, 'bar': [1, 2, 3]}
You can modify the dictionary directly if you wish:
如果您愿意，可以直接修改字典：
>>> d['baz'] = 'store me'
>>> args.baz
'store me'
Yes, it is okay to access the __dict__ attribute. It is a well-defined, tested, and guaranteed behavior.
是的，可以访问 __dict__ 属性。它是一种定义明确、经过测试且有保证的行为。
回答by msw
Is it proper to "reach into" an object and use its dictproperty?
“进入”一个对象并使用它的dict属性是否合适？
In general, I would say "no". However Namespacehas struck me as over-engineered, possibly from when classes couldn't inherit from built-in types.
一般来说，我会说“不”。然而Namespace，我觉得过度设计，可能是因为类无法从内置类型继承。
On the other hand, Namespacedoes present a task-oriented approach to argparse, and I can't think of a situation that would call for grabbing the __dict__, but the limits of my imagination are not the same as yours.
另一方面，Namespaceargparse 确实提出了一种面向任务的方法，我想不出有什么情况需要抓住__dict__，但我的想象力的极限和你的不一样。
回答by Eugene Yarmash
Straight from the horse's mouth:
If you prefer to have dict-like view of the attributes, you can use the standard Python idiom,
vars():>>> parser = argparse.ArgumentParser() >>> parser.add_argument('--foo') >>> args = parser.parse_args(['--foo', 'BAR']) >>> vars(args) {'foo': 'BAR'}— The Python Standard Library, 16.4.4.6. The Namespace object
如果您更喜欢类似 dict 的属性视图，您可以使用标准的 Python 习惯用法
vars()：>>> parser = argparse.ArgumentParser() >>> parser.add_argument('--foo') >>> args = parser.parse_args(['--foo', 'BAR']) >>> vars(args) {'foo': 'BAR'}— Python 标准库，16.4.4.6。命名空间对象
