Re: Changing the way bash expands associative array subscripts

[Chet Ramey]

On 4/6/21 12:46 PM, Koichi Murase wrote:

> Looking at another thread
> https://lists.gnu.org/archive/html/bug-bash/2021-04/threads.html#00051,
> I'm now also interested in how we can handle the indirect expansions
> for 'a[@]' and the namerefs for 'a[@]':
>
> $ declare -A a=(['@']=x [1]=y)
> $
> $ # indirect expansions
> $ iref1=a[@]; printf '<%s>' "${!iref1}"; echo
> <y><x>
> $ key=@; iref2=a[$key]; printf '<%s>' "${!iref2}"; echo
> <y><x>    # <-- unexpected

But these cases are identical. After the assignment statement, iref2 has
value 'a[@]', just like iref1. I don't see why one would be more unexpected
than the other, and they're both equivalent to ${a[@]}. Unless that's your
point?


> $ # namrefs
> $ declare -n nref1=a[@]; printf '<%s>' "$nref1"; echo
> <y x>
> $ key=@; declare -n nref2=a[$key]; printf '<%s>' "$nref2"; echo
> <y x>    # <-- unexpected

Yes, namerefs are different, but not in a way that matters here. These two
cases are identical as well. If you added `declare -p nref2', you'd see it.
(The differing output issue got fixed back in January, the result of
https://lists.gnu.org/archive/html/bug-bash/2021-01/msg00148.html)

I guess I see what your point might be, but these aren't different cases.
Variables don't carry around the kind of state that might be used to
differentiate their behavior depending on the value they got at assignment
time. There is no useful syntactic information there.

Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/