[Python-ideas] a simple namespace type

[Eric Snow]

On Sat, May 26, 2012 at 3:02 PM, Calvin Spealman <ironfroggy at gmail.com> wrote:
> On Sat, May 26, 2012 at 2:53 PM, Eric Snow <ericsnowcurrently at gmail.com> wrote:
>> Any further thoughts on this?  Unless anyone is strongly opposed, I'd
>> like to push this forward.
>
> There is no good name for such a type. "Namespace" is a bad name, because
> the term "namespace" is already a general term that describes a lot of things in
> Python (and outside it) and shouldn't share a name with a specific
> thing, this type.
> That this specific type would also be within the more general namespace-concept
> only makes that worse.
>
> So, what do you call it?

Yeah, I've seen it called at least 10 different things.  I'm certainly
open to whatever works best.  I've called it "namespace" because it is
one of the two kinds of namespace in Python: mapping ([]-access) and
object (dotted-access).  The builtin dict fills the one role and the
builtin object type almost fills the other.  I guess
"dotted_namespace" or "attribute_namespace" would work if "namespace"
is too confusing.

> Also, is this here because you don't like typing the square brackets and quotes? If
> so, does it only save you three characters and is that worth the increase to the
> language size?

This is definitely the stick against which to measure!

It boils down to this: for me dotted-access communicates a different,
more stable sort of namespace than does []-access (a la dicts).
Certainly it is less typing, but that isn't really a draw for me.
Dotted access is a little easier to read, which is nice but not the
big deal for me.  No, the big deal is the conceptual difference
inherent to access via string vs. access via identifier.

Though Python does not currently have a basic, dynamic,
attribute-based namespace type, it's trivial to make one: "class
Namespace: pass" or "type('Namespace', (), {})".  While this has been
done countless times, it's so simple that no one has felt like it
belonged in the language.  And I think that's fine, though it wouldn't
hurt to have something a little more than that (see my original
message).

So if it's so easy, why bother adding it?  Well, "class Namespace:
pass" is not so simple to do using the C API.  That's about it.  (I
*do* think people would be glad to have a basic attribute-based
namespace type in the langauge.

> A final complaint against: would the existence of this fragment
> python-learners education
> to the point that they would defer learning and practicing to use
> classes properly?

This is an excellent point.  I suppose it depends on who was teaching,
and how a new simple "namespace" type were exposed and documented.  It
certainly is not a replacement for classes, which have much more
machinery surrounding state/methods/class-ness.  If it made it harder
to learn Python then it would definitely have to bring *a lot* to the
table.

> Sorry to complain, but someone needs to in python-ideas! ;-)

Hey, I was more worried about the crickets I was hearing.  :)

-eric