Why would I use .namespace.myvar?

[Stephane Chazelas <stephane@chazelas.org>]

(not sure which of zsh-users or zsh-workers is best suited for
this discussion, I'm picking zsh-users for now but please feel
free to move to zsh-workers in follow-ups).

I didn't read the initial discussions around the introduction of
namespaces in the current development version of zsh, but from
what I can tell it means:

- "." can now be used in the name of a variable, though with
  limitations:
  * .foo, foo., a.b, .a.b, a.1, .a.1x are OK, but not
  ..foo, .foo., .1.a, foo.., a.b.c, .a.b.c
  * you can refer them as ${a.b}, but not $a.b (understandably)

- the ones starting with . (and not having them starting with .
  is discouraged, presumably because that would conflict with
  ksh93's compound variables which zsh might want to support in
  the future?) are hidden from the output of "set"/"typeset"

  and there's no way to unhide them even with typeset -h, except
  with things like:

  typeset -p ${(kM)parameters:#.*}

It's always been possible to use . (or any character or
non-character, even the empty string) in function names, so
functions are not covered in the new feature.

And unless I'm missing something, that's it.

In particular, as noted in the doc, there's no support for
ksh93's:

$ namespace foo { a=1 b=2 c=3; }; echo "${.foo.a} ${.foo.b} ${.foo.c}"
1 2 3

So why would I use a ${.mynamespace.myvar} over
$_mynamespace_myvar, $ːmynamespaceːmyvar or $𐅂mynamespace𐅂myvar
(which do work on GNU systems at least as ː, 𐅂 as well as
hundreds of other characters which look appropriately shaped for
the purpose are classified as alpha (in locales whose charmap
have them) there) for my variables which I would want namespaced?

AFAICT, that doesn't give me more guarantee of avoiding clashes,
and that means I have to use those braces.

I could also hide my _mynamespace_myvar variable with typeset
-h if I wanted to.

Is there a chance that ksh93's namespace keyword be added in the
future? Would the fact that function names have been allowing .
since forever or that .foo or .foo.1 are allowed not be a problem?
How about nested namespaces?

Is using ${.foo.bar} going to be recommended going forward for
namespacing variables in user-contributed code shipped with zsh?
Is the intention to reserve those for code included with zsh to
users can be sure not to clash with the zsh ones if they don't
use them?

Thanks
Stephane