How to call a function on "dbstop if error"

I have a large and complex function. I set "dbstop if error" at the start of the function. If the function fails for some reason it will hit dbstop if error.

At this point I wish to call a failed function which can email me the log file and other diagnostics, as well as letting me know that failure has occurred.

How can I do this?

For example, below is a function that will fail

function myFunction()

dbstop if error;

x = 1;
y = 2;
z = xy; % I will fail. After this failure, I would like the code to call a function called myFail.m

end

Answer 1

[Friedrich]

Hi,

why not using try/catch?

function myFunction()

try
    x = 1;
    y = 2;
    z = xy; % I will fail. After this failure, I would like the code to call a function called myFail.m
catch err
    myFail
end

[Matlab2010]

sadly this will not work.

the function is large and so such an approach would require placing try/ catch at each possible failure point. Not feasible in this case.

[Friedrich]

No thats not true. First line of your code is try and at the end add the catch statement. You dont need to add this at any point where it can fail.

[Matlab2010]

I take back my previous comment and agree with you having read your/Jans comments. I was wrong :(.

The reasons I thought this might not work, where 1) as the code already contains a lot of try/catch, though I guess I can just have nested try/catch and 2) the code fires other instances of matlab through a batch file as worker nodes. I now track these by writing log files.

thank you for your help/ considerations.

Answer 2

[Jan]

I can only confirm, that the TRY/CATCH method suggested by Friedrich is design to colve exactly your problem:

try
  callYourFunction()
catch ME
  % Now email the problem including a stack trace and the MException object
end

Encapsulating the function call in a TRY/CATCH block catchs all internal errors. In opposite to dbstop if error it does not impede the JIT acceleration dramatically.

If you want to enable the debugger in the editor afterwards:

try
  callYourFunction()
catch ME
  % Now email the problem including a stack trace and the MException object

    % Restart:
    dbstop if all error
    callYourFunction()
  end

But how useful is it to enable a remote and local debugging at the same time? It increases the chance, that the local user manipulates the bug locally, such that the (time delayed) external debugging will be based on an outdated source code already.