deactivate() {
    export PATH="$_OLD_D_PATH"
    export LIBRARY_PATH="$_OLD_D_LIBRARY_PATH"
    export LD_LIBRARY_PATH="$_OLD_D_LD_LIBRARY_PATH"
    export PS1="$_OLD_D_PS1"

    unset _OLD_D_PATH
    unset _OLD_D_LIBRARY_PATH
    unset _OLD_D_LD_LIBRARY_PATH
    unset _OLD_D_PS1
    unset DMD
    unset DC
    unset -f deactivate
}

_OLD_D_PATH="${PATH:-}"
_OLD_D_LIBRARY_PATH="${LIBRARY_PATH:-}"
_OLD_D_LD_LIBRARY_PATH="${LD_LIBRARY_PATH:-}"
_OLD_D_PS1="${PS1:-}"

export PATH="/root/dlang/dub:/root/dlang/dmd-2.073.2/freebsd/bin64:${PATH:-}"
export LIBRARY_PATH="/root/dlang/dmd-2.073.2/freebsd/lib64:${LIBRARY_PATH:-}"
export LD_LIBRARY_PATH="/root/dlang/dmd-2.073.2/freebsd/lib64:${LD_LIBRARY_PATH:-}"
export DMD=dmd
export DC=dmd
export PS1="(dmd-2.073.2)${PS1:-}"