--- /dev/null
+## Copyright (C) 2009-2012 VZLU Prague
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING. If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{names} =} __all_opts__ (@dots{})
+## Undocumented internal function.
+## @end deftypefn
+
+## Query all options from all known optimization functions and return a
+## list of possible values.
+
+function names = __all_opts__ (varargin)
+
+ persistent saved_names = {};
+
+ ## do not clear this function
+ mlock ();
+
+ ## guard against recursive calls.
+ persistent recursive = false;
+
+ if (recursive)
+ names = {};
+ elseif (nargin == 0)
+ names = saved_names;
+ else
+ ## query all options from all known functions. These will call optimset,
+ ## which will in turn call us, but we won't answer.
+ recursive = true;
+ names = saved_names;
+ for i = 1:nargin
+ try
+ opts = optimset (varargin{i});
+ fn = fieldnames (opts).';
+ names = [names, fn];
+ catch
+ # throw the error as a warning.
+ warning (lasterr ());
+ end_try_catch
+ endfor
+ names = unique (names);
+ [lnames, idx] = unique (tolower (names));
+ if (length (lnames) < length (names))
+ ## This is bad.
+ error ("__all_opts__: duplicate options with inconsistent case");
+ else
+ names = names(idx);
+ endif
+ saved_names = names;
+ recursive = false;
+ endif
+
+endfunction
+
+
+## No test needed for internal helper function.
+%!assert (1)
+