--- a/scripts/ChangeLog	Wed Mar 24 10:38:39 2010 +0100
+++ b/scripts/ChangeLog	Wed Mar 24 12:56:18 2010 +0100
@@ -1,3 +1,7 @@
+2010-03-24  Jaroslav Hajek  <highegg@gmail.com>
+
+	* miscellaneous/unimplemented.m: New function.
+
 2010-03-24  Jaroslav Hajek  <highegg@gmail.com>
 
 	* general/cell2mat.m: Support cells of cells.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/miscellaneous/unimplemented.m	Wed Mar 24 12:56:18 2010 +0100
@@ -0,0 +1,445 @@
+## Copyright (C) 2010 John W. Eaton
+## Copyright (C) 2010 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} {} unimplemented ()
+## Undocumented internal function.
+## @end deftypefn
+
+function unimplemented (fcn)
+
+  ## Some smarter cases, add more as needed.
+  switch (fcn)
+  case "onCleanup"
+    txt = ["onCleanup is not implemented. Consider using unwind_protect, ",...
+    "which is more versatile. For more info, type @code{help unwind_protect}."];
+
+  case "textscan"
+    txt = ["textscan is not implemented. Consider using textread or sscanf."];
+
+  case "gsvd"
+    txt = ["gsvd is currently not part of Octave. See the linear-algebra package at ",...
+    "@url{http://octave.sf.net/linear-algebra/}."];
+
+  case "linprog"
+    txt = ["Octave does not currently provide linprog. Linear programming problems may be solved ",...
+    "using @code{glpk}. Try @code{help glpk} for more info."];
+
+  case {"ode113", "ode15i", "ode15s", "ode23", "ode23s", "ode23t", "ode45", "odeget", "odeset"}
+    txt = ["Octave provides lsode for solving differential equations. For more information, ",...
+    "try @code{help lsode}.\n Matlab-compatible ODE functions are provided by the odepkg package. ",...
+    "See @url{http://octave.sf.net/odepkg/}."];
+
+  otherwise
+    if (ismember (fcn, missing_functions ()))
+
+      ## The default case.
+
+      txt = sprintf ("The %s function is not yet implemented in Octave.", fcn);
+
+    else
+      return;
+    endif
+  endswitch
+
+  txt = [txt, "\nPlease read @url{http://www.octave.org/missing.html}",...
+  "to find out how you can help with contributing missing functionality."];
+
+  warning ("Octave:missing-function",["\n", __makeinfo__(txt)]);
+
+endfunction
+
+function list = missing_functions ()
+  persistent list = {
+  "DelaunayTri", 
+  "MException", 
+  "RandStream", 
+  "TriRep", 
+  "TriScatteredInterp", 
+  "addpref", 
+  "align", 
+  "alim", 
+  "alpha", 
+  "alphamap", 
+  "annotation", 
+  "audiodevinfo", 
+  "audioplayer", 
+  "audiorecorder", 
+  "aufinfo", 
+  "auread", 
+  "auwrite", 
+  "avifile", 
+  "aviinfo", 
+  "aviread", 
+  "bar3", 
+  "bar3h", 
+  "bench", 
+  "betaincinv", 
+  "bicg", 
+  "bicgstabl", 
+  "brush", 
+  "builddocsearchdb", 
+  "bvp4c", 
+  "bvp5c", 
+  "bvpget", 
+  "bvpinit", 
+  "bvpset", 
+  "bvpxtend", 
+  "callSoapService", 
+  "calllib", 
+  "camdolly", 
+  "cameratoolbar", 
+  "camlight", 
+  "camlookat", 
+  "camorbit", 
+  "campan", 
+  "campos", 
+  "camproj", 
+  "camroll", 
+  "camtarget", 
+  "camup", 
+  "camva", 
+  "camzoom", 
+  "cdf2rdf", 
+  "cdfepoch", 
+  "cdfinfo", 
+  "cdfread", 
+  "cdfwrite", 
+  "cellplot", 
+  "checkin", 
+  "checkout", 
+  "cholinc", 
+  "clearvars", 
+  "clipboard", 
+  "cmopts", 
+  "cmpermute", 
+  "cmunique", 
+  "colordef", 
+  "colormapeditor", 
+  "comet3", 
+  "commandhistory", 
+  "commandwindow", 
+  "condeig", 
+  "coneplot", 
+  "contourslice", 
+  "copyobj", 
+  "createClassFromWsdl", 
+  "createSoapMessage", 
+  "curl", 
+  "customverctrl", 
+  "daqread", 
+  "datacursormode", 
+  "datatipinfo", 
+  "dbmex", 
+  "dde23", 
+  "ddeget", 
+  "ddesd", 
+  "ddeset", 
+  "decic", 
+  "depdir", 
+  "depfun", 
+  "deval", 
+  "dialog", 
+  "dither", 
+  "divergence", 
+  "docopt", 
+  "docsearch", 
+  "dragrect", 
+  "dynamicprops", 
+  "echodemo", 
+  "ellipj", 
+  "ellipke", 
+  "erfcinv", 
+  "errordlg", 
+  "evalc", 
+  "exifread", 
+  "expint", 
+  "export2wsdlg", 
+  "figurepalette", 
+  "filebrowser", 
+  "fill3", 
+  "findfigs", 
+  "fitsinfo", 
+  "fitsread", 
+  "flow", 
+  "fminsearch", 
+  "frame2im", 
+  "freqspace", 
+  "funm", 
+  "gallery", 
+  "gammaincinv", 
+  "gco", 
+  "getappdata", 
+  "getframe", 
+  "getpixelposition", 
+  "getpref", 
+  "gmres", 
+  "grabcode", 
+  "graymon", 
+  "gsvd", 
+  "guidata", 
+  "guide", 
+  "guihandles", 
+  "handle", 
+  "hdf", 
+  "hdf5", 
+  "hdf5info", 
+  "hdf5read", 
+  "hdf5write", 
+  "hdfinfo", 
+  "hdfread", 
+  "hdftool", 
+  "helpbrowser", 
+  "helpdesk", 
+  "helpdlg", 
+  "helpwin", 
+  "hgexport", 
+  "hgload", 
+  "hgsave", 
+  "hgsetget", 
+  "hgtransform", 
+  "hostid", 
+  "ilu", 
+  "im2frame", 
+  "im2java", 
+  "imapprox", 
+  "imformats", 
+  "import", 
+  "importdata", 
+  "inmem", 
+  "inputParser", 
+  "inputdlg", 
+  "inspect", 
+  "instrfind", 
+  "instrfindall", 
+  "interpstreamspeed", 
+  "isappdata", 
+  "iscom", 
+  "isinterface", 
+  "isjava", 
+  "isocaps", 
+  "ispref", 
+  "isprop", 
+  "isstudent", 
+  "javaArray", 
+  "javaMethod", 
+  "javaMethodEDT", 
+  "javaObject", 
+  "javaObjectEDT", 
+  "javaaddpath", 
+  "javachk", 
+  "javaclasspath", 
+  "javarmpath", 
+  "ldl", 
+  "libfunctions", 
+  "libfunctionsview", 
+  "libisloaded", 
+  "libpointer", 
+  "libstruct", 
+  "light", 
+  "lightangle", 
+  "lighting", 
+  "linkaxes", 
+  "linkdata", 
+  "linsolve", 
+  "listdlg", 
+  "listfonts", 
+  "loadlibrary", 
+  "lscov", 
+  "lsqr", 
+  "makehgtform", 
+  "material", 
+  "matlabrc", 
+  "maxNumCompThreads", 
+  "memmapfile", 
+  "memory", 
+  "metaclass", 
+  "methodsview", 
+  "minres", 
+  "mlint", 
+  "mlintrpt", 
+  "mmfileinfo", 
+  "mmreader", 
+  "movegui", 
+  "movie", 
+  "movie2avi", 
+  "msgbox", 
+  "multibandread", 
+  "multibandwrite", 
+  "native2unicode", 
+  "noanimate", 
+  "ode113", 
+  "ode15i", 
+  "ode15s", 
+  "ode23", 
+  "ode23s", 
+  "ode23t", 
+  "ode23tb", 
+  "ode45", 
+  "odefile", 
+  "odeget", 
+  "odeset", 
+  "odextend", 
+  "onCleanup", 
+  "open", 
+  "openfig", 
+  "opengl", 
+  "openvar", 
+  "ordeig", 
+  "ordqz", 
+  "ordschur", 
+  "padecoef", 
+  "pagesetupdlg", 
+  "pan", 
+  "parseSoapResponse", 
+  "path2rc", 
+  "pathtool", 
+  "pcode", 
+  "pdepe", 
+  "pdeval", 
+  "pie3", 
+  "playshow", 
+  "plotbrowser", 
+  "plotedit", 
+  "plottools", 
+  "polyeig", 
+  "prefdir", 
+  "preferences", 
+  "printdlg", 
+  "printopt", 
+  "printpreview", 
+  "profile", 
+  "profsave", 
+  "propedit", 
+  "propertyeditor", 
+  "publish", 
+  "qmr", 
+  "quad2d", 
+  "questdlg", 
+  "randi", 
+  "rbbox", 
+  "rectangle", 
+  "recycle", 
+  "reducepatch", 
+  "reducevolume", 
+  "resample", 
+  "reset", 
+  "rgbplot", 
+  "rmappdata", 
+  "rmpref", 
+  "root", 
+  "rotate", 
+  "rotate3d", 
+  "rsf2csf", 
+  "saveas", 
+  "selectmoveresize", 
+  "sendmail", 
+  "serial", 
+  "setappdata", 
+  "setpixelposition", 
+  "setpref", 
+  "showplottool", 
+  "shrinkfaces", 
+  "smooth3", 
+  "snapnow", 
+  "sound", 
+  "soundsc", 
+  "ss2tf", 
+  "stream2", 
+  "stream3", 
+  "streamline", 
+  "streamparticles", 
+  "streamribbon", 
+  "streamslice", 
+  "streamtube", 
+  "strings", 
+  "subvolume", 
+  "superclasses", 
+  "support", 
+  "surf2patch", 
+  "symmlq", 
+  "syntax", 
+  "tetramesh", 
+  "texlabel", 
+  "textscan", 
+  "textwrap", 
+  "tfqmr", 
+  "timer", 
+  "timerfind", 
+  "timerfindall", 
+  "timeseries", 
+  "toolboxdir", 
+  "tscollection", 
+  "tstool", 
+  "uibuttongroup", 
+  "uicontextmenu", 
+  "uicontrol", 
+  "uigetdir", 
+  "uigetfile", 
+  "uigetpref", 
+  "uiimport", 
+  "uimenu", 
+  "uiopen", 
+  "uipanel", 
+  "uipushtool", 
+  "uiputfile", 
+  "uiresume", 
+  "uisave", 
+  "uisetcolor", 
+  "uisetfont", 
+  "uisetpref", 
+  "uistack", 
+  "uitable", 
+  "uitoggletool", 
+  "uitoolbar", 
+  "uiwait", 
+  "undocheckout", 
+  "unicode2native", 
+  "unloadlibrary", 
+  "unmesh", 
+  "usejava", 
+  "userpath", 
+  "validateattributes", 
+  "verLessThan", 
+  "viewmtx", 
+  "visdiff", 
+  "volumebounds", 
+  "waitbar", 
+  "waitfor", 
+  "warndlg", 
+  "waterfall", 
+  "wavfinfo", 
+  "wavplay", 
+  "wavrecord", 
+  "web", 
+  "whatsnew", 
+  "whitebg", 
+  "wk1finfo", 
+  "wk1read", 
+  "wk1write", 
+  "workspace", 
+  "xlsfinfo", 
+  "xlsread", 
+  "xlswrite", 
+  "xmlread", 
+  "xmlwrite", 
+  "xslt", 
+  "zoom",
+  };
+endfunction

--- a/src/ChangeLog	Wed Mar 24 10:38:39 2010 +0100
+++ b/src/ChangeLog	Wed Mar 24 12:56:18 2010 +0100
@@ -1,3 +1,12 @@
+2010-03-24  Jaroslav Hajek  <highegg@gmail.com>
+
+	* variables.cc (Fmissing_function_hook): New pseudo-variable.
+	(Vmissing_function_hook): New static var.
+	(maybe_missing_function_hook): New function.
+	* variables.h: Declare it.
+	* pt-id.cc (tree_identifier::eval_undefined_error): Call it here.
+	* oct-parse.yy (feval (const std::string&, ...)): Also here.
+
 2010-03-23  Jaroslav Hajek  <highegg@gmail.com>
 
 	* data.cc (Frem, Fmod): New DEFUNs.

--- a/src/oct-parse.yy	Wed Mar 24 10:38:39 2010 +0100
+++ b/src/oct-parse.yy	Wed Mar 24 12:56:18 2010 +0100
@@ -4034,7 +4034,11 @@
   if (fcn.is_defined ())
     retval = fcn.do_multi_index_op (nargout, args);
   else
-    error ("feval: function `%s' not found", name.c_str ());
+    {
+      maybe_missing_function_hook (name);
+      if (! error_state)
+        error ("feval: function `%s' not found", name.c_str ());
+    }
 
   return retval;
 }

--- a/src/pt-id.cc	Wed Mar 24 10:38:39 2010 +0100
+++ b/src/pt-id.cc	Wed Mar 24 12:56:18 2010 +0100
@@ -45,6 +45,10 @@
   int l = line ();
   int c = column ();
 
+  maybe_missing_function_hook (name ());
+  if (error_state)
+    return;
+
   if (l == -1 && c == -1)
     ::error ("`%s' undefined", name ().c_str ());
   else

--- a/src/variables.cc	Wed Mar 24 10:38:39 2010 +0100
+++ b/src/variables.cc	Wed Mar 24 12:56:18 2010 +0100
@@ -2376,3 +2376,22 @@
 {
   return SET_INTERNAL_VARIABLE (whos_line_format);
 }
+
+static std::string Vmissing_function_hook = "unimplemented";
+
+DEFUN (missing_function_hook, args, nargout,
+    "-*- texinfo -*-\n\
+@deftypefn {Built-in Function} {@var{val} =} missing_function_hook ()\n\
+@deftypefnx {Built-in Function} {@var{old_val} =} missing_function_hook (@var{new_val})\n\
+Query or set the internal variable that allows setting a custom hook function\n\
+called when an uknown identifier is requested.\n\
+@end deftypefn")
+{
+  return SET_INTERNAL_VARIABLE (missing_function_hook);
+}
+
+void maybe_missing_function_hook (const std::string& name)
+{
+  if (! Vmissing_function_hook.empty ())
+    feval (Vmissing_function_hook, octave_value (name));
+}

--- a/src/variables.h	Wed Mar 24 10:38:39 2010 +0100
+++ b/src/variables.h	Wed Mar 24 12:56:18 2010 +0100
@@ -135,4 +135,6 @@
 extern OCTINTERP_API void clear_variable (const std::string& nm);
 extern OCTINTERP_API void clear_symbol (const std::string& nm);
 
+extern OCTINTERP_API void maybe_missing_function_hook (const std::string& name);
+
 #endif