dnl CHAMPLAIN_CONFIG_COMMANDS is like AC_CONFIG_COMMANDS, except that:

dnl

dnl     1) It redirects the stdout of the command to the file.

dnl     2) It does not recreate the file if contents did not change.

dnl

dnl (macro copied from CAIRO)

AC_DEFUN([CHAMPLAIN_CONFIG_COMMANDS],

[dnl

        AC_CONFIG_COMMANDS($1,

        [

                _config_file=$1

                _tmp_file=champlainconf.tmp

                AC_MSG_NOTICE([creating $_config_file])

                {

                        $2

                } >> "$_tmp_file" ||

                AC_MSG_ERROR([failed to write to $_tmp_file])

                if cmp -s "$_tmp_file" "$_config_file"; then

                  AC_MSG_NOTICE([$_config_file is unchanged])

                  rm -f "$_tmp_file"

                else

                  mv "$_tmp_file" "$_config_file" ||

                  AC_MSG_ERROR([failed to update $_config_file])

                fi

        ], $3)

])