[Changeset] Fcellfun problem with ErrorHandler access to message/id and count..

[John W. Eaton]

On 28-Jul-2008, David Bateman wrote:

| The Fcellfun function has the capability of defining an ErrorHandler
| function that addresses any errors that occur in the main function. This
| error handler is passed the same arguments as the main function but
| prepended with a structure containing the last error message, id and the
| cell array index at which the error occurred. Thomas Treichl pointed out
| to me that in both 3.0.1+ and 3.1.51+ the prepended value is incorrect.
| 
| Firstly the index that is passed is zero based, when in should be
| one-based, and so we have to add one to the count value in the prepended
| structure. Secondly it appears that the error message and id strings
| that are passed are empty. The way these messages are currently
| generated is to call Flasterr and get the strings from this call. The
| reason it was done this way previous is, if I remember correctly, that
| John didn't want to expose the Vlast_error_message and Vlast_error_id
| variables to be changed outside of the error.cc file. I'm not sure why 
| the call to lasterr doesn't work, but suggest that we add a few
| functions to access the Vlast_error_message and Vlast_error_id variables
| without allowing the variables to be changed, as this would be faster
| than having to call the lasterr function through feval.
| 
| I therefore suggest the attached patch for 3.1.51+.. With this change I
| see the following
| 
| function n = myhand (S, varargin)
| >   disp (S);
| >   n = NaN;
| > endfunction
| octave:2>
| octave:2> cellfun(@factorial,{-1,3},'ErrorHandler', at myhand);
| {
|   identifier =
|   message = factorial: n must all be nonnegative integers
|   index =  1
| }
| octave:3> lasterror ()
| ans =
| {
|   message = factorial: n must all be nonnegative integers
|   identifier =
|   stack =
|   {
|     file =
| /home/adb014/octave/code/octave-build/../octave-hg/scripts/specfun/factorial.m
|     name = factorial
|     line =  32
|     column =  5
|   }
| 
| }
| 
| Unfortunately unless we can figure out why the lasterr call didn't work
| I see no fix for 3.0.1+ that doesn't alter the error.h file and thus the
| 3.0.x API which we want to keep unaltered. So maybe this is a bug that
| won't be fixed in 3.0.x.

The following patch seems to fix the problem for me.

I also applied your patch as it seems a cleaner way to do this job
instead of calling Flasterr.

Thanks,

jwe

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