idea for idempotent ENV updates

[coolaj86]

I was just noticing an interesting, idempotent way to update the PATH while trying to track down an issue with my cargo config:

PATH="$(fn_export "$PATH" "${HOME}/bin")"
PATH="$(fn_export "$PATH" "${HOME}/.local/bin")"

fn_export() {(
    b_path="${1}"
    b_new_path="${2}"

    case ":${b_path}:" in
        *:"${b_new_path}":*)
            ;;
        *)
            # Prepending path in case a system-installed path needs to be overridden
            b_path="${b_new_path}:${b_path}"
            ;;
    esac

    echo "${b_path}"
);}

What I like:

• idempotent

What I don't like:

• non-standard
• non-portable (bash and fish would need different implementations)