Error logging, MException messages get truncated

I'm running a lot of separate functions on a lot of datasets. It's very time consuming and quite prone to errors so I devised the following set up in my code so I can see where things went wrong afterwards. Since the errors may occur in a sub function of a subfuntion, I embedded a small loop that loops through the stack of the MException block. Since I'm working with diary, I tried to display all information possible into the command window so it gets picked up in the log file.

function allAnalyses

logfilename = strcat('Log allAnalyses.m_',datestr(now,'dd-mm-yy HHMM'));
diary(logfilename)
tic
disp(strcat('Log van alleAnalyses.m_',datestr(now,'dd-mm-yy HHMM')));

try
    disp('analysis_1');
    analysis_1;  % the function to employ
catch Error
    warning('Error in analysis_1;')
disp(Error);
In_subfunction = Error.stack;
        for i = 1:size(In_subfunction,1);
            In_subfunction = Error.stack(i,:)
        end
Reason = Error.cause 
end 
toc
% etc, 20 more blocks like this. 
diary off

This results in text in the diary like:

Warning: Fout in analysis_1.m; 
> In allAnalyses (line 110) 
  MException with properties:

      identifier: 'MATLAB:xlsread:FileNotFound'
         message: 'XLSREAD unable to open file '\\xxx\tools$\yyyy\Pro...'
           cause: {0x1 cell}
           stack: [1x1 struct]

In_subfunction = 

      file: 'C:\Program Files\MATLAB\R2015a\toolbox\matlab\iofun\xlsread.m'
      name: 'xlsread'
      line: 128

The problem here lays with the truncation of the message within the MException. Off course I need to know which file XLSREAD wasn't able to open. So how do I approach this?

Answer 1

[Guillaume]

Don't use disp to show the exception but make your own display, e.g:

fprintf('   identifier: %s\n   message: %s\n', Error.identifier, Error.message);

Note that I don't show the cause and stack fields, since to properly display these you'd have to recurse through the cell arrays / structures.

Answer 2

[Walter Roberson]

for fn = fieldnames(Error)
  fprintf('%15s:', fn);
  disp(Error.(fn));
end

You are using disp() on an entire structure. Just like disp() of a cell array, the contents of fields may be summarized. The work-around is to not disp() the entire structure.

[jasper111]

Small alteration

for fn = fieldnames(Error)'
  fprintf('%15s:', fn{:});
  disp(Error.(fn{:}));
end

Thanks a 1000 for the explanation. Structures are new to me, this explains a lot.