On Dec 23, 2015 7:00 AM, "Chris Angelico" <ros...@gmail.com> wrote:
> On Wed, Dec 23, 2015 at 11:46 PM, Neal Becker <ndbeck...@gmail.com> wrote:
> > Sometimes I want to collect attributes on an object. Usually I would make
> > an empty class for this. But it seems unnecessarily verbose to do this. So
> > I thought, why not just use an Object? But no, an instance of Object
> > apparantly can't have an attribute. Is this intentional?
>
> Yes; there are other uses of object() that benefit from being
> extremely compact. You can use types.SimpleNamespace for this job, or
> you can create the empty class as you're describing. (Chances are you
> can give the class a meaningful name anyway.)
Its more that if you give object() an instance dict, all objects
inheriting from object (i.e., all of them) must have an instance dict,
which would make __slots__ and its benefits impossible.
Another cross-version option:
>>> bag = type("AttrBag", (), {})()
>>> bag.spam = 2
>>> bag.spam
2
You can even sneak in keyword arguments like SimpleNamespace supports
by passing them in the namespace dict (the third argument):
>>> bag = type("AttrBag", (), dict(spam=3))()
>>> bag.spam
3
Of course, using this you lose easy access to the 'AttrBag' class, but
in most cases you shouldn't need it. If you do, just make it a
regular class as has been suggested, or save off a reference to the
class before instantiating.
No comments on how ugly this is, though :)
--
Zach
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