[Python-ideas] a simple namespace type

[Eric Snow]

On Thu, May 24, 2012 at 5:59 AM, Yuval Greenfield <ubershmekel at gmail.com> wrote:
> On Tue, May 22, 2012 at 7:26 PM, Eric Snow <ericsnowcurrently at gmail.com>
> wrote:
>>
>> Below I've included a pure Python implementation of a type that I wish
>> was a builtin.  I know others have considered similar classes in the
>> past without any resulting change to Python, but I'd like to consider
>> it afresh[1][2].
>> [...]
>
> I've implemented this a few times as well. I called it "AttributeDict" or
> "Record".
>
>
> I think adding an __iter__ method would be beneficial. E.g.
>
> class  SimpleNamespace :
>      def __init__(self, **kwargs):
>          self.__dict__.update(kwargs)  # or self.__dict__ = kwargs
>          self.__iter__ = lambda: iter(kwargs.keys())

I'd like to limit the syntactic overlap with dict as much as possible.
 Effectively this is just a simple but distinct facade around dict to
give a namespace with attribute access.  I suppose part of the
question is how much of the Mapping interface would belong instead to
a hypothetical Namespace interface. (I'm definitely _not_ proposing
such an unnecessary extra level of abstraction).

Regardless, if you want to do dict things then you can get the
underlying dict using vars(ns) or ns.__dict__ on your instance.
Alternately you can subclass the SimpleNamespace type to get all the
extra goodies you want, as I showed with the Namespace class at the
bottom of my first message.

> Why do we need this imo:
>
> * sometimes x.something feels better than x['something']
> * to ease duck-typing, making mocks, etc.
> * Named tuple feels clunky for certain dynamic cases (why do I need to
> create the type for a one-off?)

Yup.

> I wonder if SimpleNameSpace should allow __getitem__ as well...

Same thing: just use vars(ns) or a subclass of SimpleNamespace.

-eric