Re: Functions takes arrays and outputting another array

[Jesse Hathaway]

On Fri, Mar 31, 2023 at 11:59 AM uzibalqa <uzibalqa@proton.me> wrote:
>
> I want to make a bash function that takes two arrays and outputs another 
> array.
>
> Here I use "typeset".  Should I use "declare" instead as in (declare -n 
> _array1="$1" _array2="$2") ?
>
> For the output, I have thought about introducing a null.  Is this the correct 
> way to output arrays
> from a function?

Another fun way to pass arrays by value, though not particularly
performant, is to use stdin and stdout to pass their values. As an example
here I pass an array to a function via stdin and then pass the
result via stdout.

#!/bin/bash

function type_value {
        IFS='=' read -r _ var
        printf '%s\n' "$var"
}

function reverse_array {
        read -r val
        eval 'a='"$val"
        declare -a rev_a
        # shellcheck disable=SC2154
        len=${#a[@]}
        for ((i = (len - 1); i >= 0; i--)); do
                rev_a+=("${a[i]}")
        done
        declare -p rev_a | type_value
}

# shellcheck disable=SC2034
butter=(a b c d e f g)
eval 'bubbles='"$(declare -p "butter" | type_value | reverse_array)"
# shellcheck disable=SC2154
declare -p bubbles