Re: [Help-bash] indirection for arrays

[John Kearney]

Am 05.05.2012 22:16, schrieb Bill Gradwohl:

Via a web site reference, Dan Douglas (Thank You) provided something akin to this:

func() {
    local -a 'keys=("${!'"$1"'address@hidden")' 
...
...
}

declare -a myArray=(1 2 3)

func 'myArray'

Neat trick! Took me a while to figure out how it works. The single quotes in particular stopped me in my tracks for a while.

Can I rely on this in future versions of bash, or is this a side effect that might disappear some day? I can find no documentation that says specifically it's supported.

Also, since indirection requires the ! immediately after a {, this means indirection can never be on the left hand side of an assignment. Correct?

The "trick" above is doing a type of indirection by getting the parser to cooperate in a sneaky fashion. At least that's my analysis.

Is there some other mechanism ("trick") besides eval that can do indirection on the left hand side of an assignment? A mechanism that can be relied on in future releases.

--
Bill Gradwohl

off the top of my head you can also do this sort of thing.
assignment is easier than recovery.

since something like bash 3.1 ish
printf -v "${1}"  "%s"   "Value"
printf -v "${1}[1]"  "%s"   "Value"

since something like bash 4.2 ish,
declare -g "${1}=jkjoiij"

again if your working with integers
: $(( ${1}[1]=3 ))
let "${1}[1]=4"
 

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