what is the right way to treat Python argparse.Namespace() as a dictionary?

If I want to use the results of argparse.ArgumentParser(), which is a Namespace object, with a method that expects a dictionary or mapping-like object (see collections.Mapping), what is the right way to do it?

    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?

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.

You can access the namespace's dictionary with vars():

    >>> 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:

    >>> 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.

From: stackoverflow.com/q/16878315

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