MATLAB: How to pass additional variables with serial callback function (R2020b)

Question

I am working on continuously displaying data on a gui that comes through a serial port. The data comes in form of one string with a "LF/CR" at the end. The obvious idea is to create a callback function that updates the text field of the gui each time that terminator is detected. The problem is that the callback function need the be in the form of

function mycallback(src, evt)
    ...
end

but also needs the handles of the gui.

With older Matlab Versions I would just use

configureTerminator(s,"CR/LF")
s.BytesAvailableFcnMode = 'terminator';
s.BytesAvailableFcn = {@mycallback,guiHandles};
function mycallback (src, evt, handles)
    ...
end

But with the newer versions (I am using 2020b) I am forced to use

configureTerminator(s,"CR/LF")
configureCallback(s,"terminator",@mycallback)

I hoped I could just use

configureCallback(s,"terminator",{@mycallback, guiHandles})

or something like that but that doesnt seem to work as configureCallback requires a @callbackfcn and does not accept arrays or cells. I also couldn't find anything on the internet for this matlab version aswell.

Any ideas on how to solve that problem?

Thanks in advance

Moritz

Answer 1

What about an anonymous function_

% [EDITED] Typo fixed: () around parameters of anonymous function, not {}!
configureCallback(s, "terminator", @(src, evt) mycallback(src, evt, handles))

The ugly solution would be to store the handles persistently in the callback:

function mycallback(src, evt)
persistent handles
if nargin == 1
    handles = src;
    return;
end
...
end

Then call the callback after creating the handles:

mycallback(handles);

This is prone to bugs, because you might forget to update the persistent data. The anonymous function is a more direct approach.