Re: local -r for arrays

[Marco Ippolito]

On 25/10/2020 21:32, Lawrence Velázquez wrote:
> > On Oct 25, 2020, at 2:42 PM, Marco Ippolito <maroloccio@gmail.com> wrote:
> >
> > but I can't do this:
> >
> > g2() {
> >     local -r a=(2 "$@")
> >     echo "${a[@]}"
> > }
> >
> > f2() {
> >     local -r a=(1)
> >     g2 "${a[@]}"
> > }
> >
> > f2 -> error "a: readonly variable"
>
> Note that your test case works if g2() uses local -a.
>
> g2() {
>     local -ar a=(2 "$@")
>     echo "${a[@]}"
> }
>
> --
> vq

True, but even if the "works":

set -x

# declare -ar a=(3)

g2() {
    local -ar a=(2 "$@")
    echo "${a[@]}"
}

f2() {
    local -ar a=(1)
    g2 "${a[@]}"
}

f2 ->
+ f2
+ a=(1)
+ local -ar a
+ g2 1
+ a=(2 "$@")
+ local -ar a
+ echo 2 1
2 1

uncommenting the outer array declaration makes it fail again:

f2 -> a: readonly variable

It is as if we were "borrowing" an outer array in the two-step
approach highlighted by João, before we set "-ar" on a local
with the same name.