Re: [PATCH 1/3] Extended ksh compatibility: namespace parameter syntax

[Phil Pennock <zsh-workers+phil.pennock@spodhuis.org>]

On 2023-05-19 at 23:54 -0700, Bart Schaefer wrote:
> On Fri, May 19, 2023 at 7:06 PM Phil Pennock
> <zsh-workers+phil.pennock@spodhuis.org> wrote:
> > AFAICT, in zsh, .a.b=c is assigning to var b in namespace a, while a.b=c
> > is setting the b attribute of the compound variable a.
> 
> As presently implemented, there's no difference.  The latter is
> supported by the parser but should be considered a reserved syntax;
> some sort of compound variable feature is a possible future
> application.

Sorry, I thought I'd fixed that typo before sending.

In _ksh_.

I played with ksh to evaluate the behavior, which didn't match what was
said upthread, which is why I spoke up to clarify the distinction.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~8< ksh >8~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% ksh
$ echo ${.sh.version}
Version AJM 93u+ 2012-08-01
$ PS1='ksh$ '
ksh$ foo=( alpha=first beta=second ) # compound var
ksh$ namespace bar { alpha=one beta=two ; }
ksh$ echo ${foo}
( alpha=first beta=second )
ksh$ echo ${.foo}

ksh$ echo ${bar}

ksh$ echo ${.bar}
alpha beta
ksh$ foo.gamma=third
ksh$ echo $foo
( alpha=first beta=second gamma=third )
ksh$ .bar.gamma=three
ksh$ echo ${.bar}
alpha beta
ksh$ namespace bar { echo $gamma; }
three
ksh$ echo ${.bar.gamma}
three
ksh$ echo ${@foo}
typeset -C
ksh$ echo ${@bar}

ksh$ echo ${@.bar}

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~8< ksh >8~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I don't know what's going on with `echo ${.bar}`, it's undocumented in
my man-page and the inability to use ${@vname} to get details about it
suggests perhaps it shouldn't expand?
(  ksh ${@vname} ~~ zsh ${(t)vname}  )

So, to match the intent of ksh as I understand it:
 * .identifier.x is always treating identifier as a namespace
 * identifier.x is always treating identifier as a compound var
 * this is consistent across assignment LHS and expansion

-Phil