While you could use the usual suspects, like a dictionary, a NamedTuple, a dataclass, or even an “empty” class, there is yet another way: SimpleNamespace.

>>> from types import SimpleNamespace
>>> simple_ns = SimpleNamespace(a=1, b="two")
>>> simple_ns
namespace(a=1, b='two')
>>> simple_ns.a
1
>>> simple_ns.b
'two'
>>>

implementation

This builtin is implemented in C, but the Python docs show how it would look like in Python:

class SimpleNamespace:
    def __init__(self, /, **kwargs):
        self.__dict__.update(kwargs)

    def __repr__(self):
        items = (f"{k}={v!r}" for k, v in self.__dict__.items())
        return "{}({})".format(type(self).__name__, ", ".join(items))

    def __eq__(self, other):
        return self.__dict__ == other.__dict__

That is the reason why we have this nice representation.

>>> simple_ns
namespace(a=1, b='two')

As a plus, you can even compare instances by attribute comparison, and not only by id!

>>> another_ns = SimpleNamespace(a=1, b="two")
>>> simple_ns == another_ns
True
>>> simple_ns is another_ns
False

why not a class?

>>> class NS:
...     pass
... 
>>> class_ns = NS()
>>> class_ns.a = 1
>>> class_ns.b = "two"
>>> class_ns
<__main__.class_ns object at 0x7f01cc670c18>

>>> another_class_ns = NS()
>>> another_class_ns.a = 1
>>> another_class_ns.b = "two"
>>> class_ns == another_class_ns
False
>>>

fun fact

When you have a look at the above implementation, it looks like only the dictionaries are compared - but this is not true:

>>> simple_ns == class_ns
False

The reason is simple. The above Python implementation is not complete.

The C implementation also performs a type check.

static PyObject *
namespace_richcompare(PyObject *self, PyObject *other, int op)
{
    if (PyObject_IsInstance(self, (PyObject *)&_PyNamespace_Type) &&
            PyObject_IsInstance(other, (PyObject *)&_PyNamespace_Type))
        return PyObject_RichCompare(((_PyNamespaceObject *)self)->ns_dict,
                                   ((_PyNamespaceObject *)other)->ns_dict, op);
    Py_INCREF(Py_NotImplemented);
    return Py_NotImplemented;
}

I created a bug report on the cpython issue tracker, let’s see what the core developers think about it. Update 2020-11-14 My pull request was merged.

why not just object?

>>> obj = object()
>>> obj
<object object at 0x7f01cddfe3c0>
>>> obj.a = 1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'a'

So, there are several reasons, but reason nr. 1 is, that you cannot add attributes.

thanks

Thanks Anthony Sottile for sharing his video easy fake objects with python’s SimpleNamespace