MATLAB: Access arbitrary class from MATLAB Engine interface

classMATLABmatlab enginemex

Using the MATLAB Engine interface, it is possible to access most data types such as numerical arrays, cells, structs, etc.
Is it also possible to access arbitrary classes such as an MException? If so, how? Just access the fields using mxGetField() etc. as in the case of structs? I am interested in MException in particular.
EDIT: I tried this, but unfortunately MATLAB (not the engine program, but the MATLAB process) crashes whenever I tried to call engGetVariable() on a variable of class MException. I'm on OS X. I would appreciate any suggestions about possible workarounds. Note that because of this crash, it is simply not safe to pass arbitrary variable names to engGetVariable(). There's always a chance it would crash MATLAB.

Best Answer

A trick is to convert any OOP class object to a regular structure in the MATLAB side:
ME = MException('a:b','err');
s = struct(ME);
Note that a warning is issued that any private, protected, or hidden properties of the object will become public fields in the new structure:
>> s
s = 
             type: {[0]  ''}
    hasBeenCaught: 0
       identifier: 'a:b'
          message: 'err'
            cause: {}
            stack: [0x1 struct]
     defaultstack: [0x1 struct]
        arguments: {}
Now you can retrieve the new variable using the Engine API, and handle it as a regular structure:
mxArray *s = engGetVariable(ep, "s");
mxArray *identifier = mxGetField(s, 0, "identifier");
mxArray *message = mxGetField(s, 0, "message");
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