anchor.diff:  assert usbSupport   -> libusb != null && ! udevSupport; # libusb won't be used if udev is avaliable
   assert sambaSupport -> samba != null;
   assert vdpauSupport -> libvdpau != null && ffmpeg.vdpauSupport;
  +assert pulseSupport -> pulseaudio != null;
   
   stdenv.mkDerivation rec {
       name = "xbmc-12.1";
  
positive.code: , libusb ? null, usbSupport ? false
  , samba ? null, sambaSupport ? true
  # TODO: would be nice to have nfsSupport (needs libnfs library)
  , libvdpau ? null, vdpauSupport ? true
  }:
  
  assert dbusSupport  -> dbus_libs != null;
  
negative.code:       ffmpeg libmpeg2 libsamplerate libmad
        libogg libvorbis flac
        lzo libcdio libmodplug libass
        sqlite mysql nasm avahi libdvdcss lame
        curl bzip2 zip unzip glxinfo xdpyinfo
      ]
      ++ lib.optional dbusSupport dbus_libs
      ++ lib.optional udevSupport udev
      ++ lib.optional usbSupport libusb
      ++ lib.optional sambaSupport samba
      ++ lib.optional vdpauSupport libvdpau
      ++ lib.optional pulseSupport pulseaudio;
  
      dontUseCmakeConfigure = true;
  
  