gen.source.fromto

#!/bin/bash
case $optional_flag in
 1)
    if [[ -z "${keywords[$tovar]}" ]] ; then
        eval "declare -A keywords[$tovar]=\"\${$fromvar}\""
    elif [[ "${keywords[$tovar]}" != "${!fromvar}" ]] ; then
        echo "gen.source.fromto error: in {${filename}} | {${keywords[sname]}}, folder {/${PWD##*/}}: customized {$tovar} value {${!fromvar}} /= already there value ${keywords[$tovar]}. Comment: {$fromto_comment}" 
        exit 64
    fi
    ;;
 0)
    if [[ -z "${keywords[$tovar]}" ]] ; then
        eval "declare -A keywords[$tovar]=\"\${$fromvar}\""
    elif [[ "${keywords[$tovar]}" != "${!fromvar}" ]] ; then
        echo "gen.source.fromto warning: in {${filename}} | {${keywords[sname]}}, folder {/${PWD##*/}}: attempted to othercust customize {$tovar} value {${!fromvar}}, but value ${keywords[$tovar]} is already there. othercust not mandatory, given up. Comment: {$fromto_comment}"
    fi
    ;;
 *)
    echo "gen.source.fromto warning: in {${filename}} | {${keywords[sname]}}, folder {/${PWD##*/}}: the script was called without optional_flag specified. Comment: {$fromto_comment}"
    if [[ -z "${keywords[$tovar]}" ]] ; then
        eval "declare -A keywords[$tovar]=\"\${$fromvar}\""
    elif [[ "${keywords[$tovar]}" != "${!fromvar}" ]] ; then
        echo "gen.source.fromto error: in {${filename}} | {${keywords[sname]}}, folder {/${PWD##*/}}: customized {$tovar} value {${!fromvar}} /= already there value {${keywords[$tovar]}}. Comment: {$fromto_comment}"
        exit 64
    fi
    ;;
esac