Problem with dbstop if error in 2018b

After downloading Matlab 2018b, I started having the following problem using the command dbstop if error:

My code will stop at the error as usual but then at some point later as I am debugging (typing variable names in the command line to check their values, etc.), the debugger will stop at line 43 of getArrayEditorBrushCache which reads:

eval(['I = I' subsstr ';']);

Then I have to type dbclear if error to escape the debugger and start my program over.

This is happening to me in many of my programs where dbstop if error was working fine in previous versions of Matlab. Any ideas for how to solve this or is this just a new bug?

Answer 1

[madhan ravi]

When it occurs type

dbquit % help dbquit to know more

Answer 2

[Stefano]

It was partially discussed in https://it.mathworks.com/matlabcentral/answers/353758-matlab-beep-at-zooming-in-plot-and-evaluating-variables

There is an awful (IMHO) piece of code for taking the indexes of an array:

parenStart = strfind(varName,'(');
subsstr = '';
if ~isempty(parenStart)
    subsstr = varName(parenStart:end);
    varName = varName(1:parenStart(1)-1);    
end

And when trying to index the variable I:

if ~isempty(subsstr)
    eval(['I = I' subsstr ';']);
end

it produces an error if varName was (in) (part of) an array of structures, objects, or symilar types with a dot, like:

struct(5).fieldname

I don't have the time to make a patch, and in any case I think it should be addressed by MathWorks...

[Jan]

A patch might be:

parenStart = strfind(varName, '(');
subsstr = '';
if ~isempty(parenStart)
    parentEnd = strfind(varName, ')');
    subsstr   = varName(parenStart(1):parentEnd(1));
    varName   = varName(1:parenStart(1)-1);    
end

Did I mention already that eval is a shot in your knee?! This is another example, although here this command is not the actual cause of the error. Such partial hand made parsing of code is extremely prone to bugs. Matlab does have perfect tools for parsinge a line of code already, so why re-inventing a square wheel?

[Andrei]

Jan, what these users are reporting, is the bug in Mathworks code (eval including). I came across this myself and it is very annoying. I cannot patch this because on my system I cannot write to Matlab installation folder.

[Jan]

@Andrei: Please report this bug to MathWorks.

[Stefan]

@Andrei: I have the same bug and permission problem.

A temporal workaround is to modify getArrayEditorBrushCache.m according to Jan's above patch and save it into your working folder. For me, this perfectly solved the issue.

[Adrian Cherry]

Was this ever reported as a bug to Mathworks? I've just come across it in R2023a and it's f****ing annoying.

[Yinjie]

% it works
if ~isempty(subsstr)
    try
        eval(['I = I' subsstr ';']);
    catch
        I = false;
    end
end