[BASH] Watch Func

function watch() {
    local varName=$1
    local prefix=$2 # Optionnal
    local var

    eval var=\$$varName

    [[ $# -ge 2 ]] && echo "${prefix} : ${var}" || echo "${varName} : ${var}"
}

function test() {
    local var a;

    a=42

    watch a
    watch a "a currently has the value"
}

test