optional_depends perl                   \
                 "--with-perl"          \
                 "--without-perl"       \
                 "enable perl bindings" &&
optional_depends python                   \
                 "--with-python"          \
                 "--without-python"       \
                 "enable python bindings" &&
optional_depends swig             \
                 "--with-swig"    \
                 "--without-swig" \
                 "enable swig"    &&
optional_depends lua51                   \
                 "--with-lua"          \
                 "--without-lua"       \
                 "enable lua51 bindings" &&
optional_depends gnutls           \
                 "" ""            \
                 "enable gnu tls" &&
optional_depends libgcrypt          \
                 "" ""              \
                 "enable libgcrypt" &&
optional_depends gtk-doc             \
                 "--enable-gtk-doc"  \
                 "--disable-gtk-doc" \
                 "use gtk-doc to build documentation"
