Let an Object Instance work on Calling Object

Hello MatLabers

I'm trying to implement some simple Matlab OO classes: I have one class (DataLoader) with a method/function (loadABCData) and another class (DataSet) with attributes/properties (stream, nfiles, stuff) as well as methods (loadData, doSomeCalc).

What I would like to do: Is to be able to do something like the following:

myDS = DataSet;  % get that new Object
myDs.loadData;   % load Data using a DataLoaderObject

so that I finally can access the properties of my object that have been filled in by my DataLoaderObject i.e.:

foo = myDS.stream(:,1:3);

What I have so far:

The data loading is done in the DataLoader.loadABCData function that I have located in loadABCData.m (Folder: @DataLoader). The implementation of DataSet.loadData looks as follows:

function loadData(obj)
  loader = DataLoader;     % make the DataLoader Object for Reading
  loader.loadABCData(obj); % call the loadABCData and give it the handle
                           % to the original Object where I would like to
                           % have the Data filled in
  delete(loader);          % remove my DataLoader again
end

in the DataLoader itself, the loadABCData function looks somehow like this:

function loadABCData(obj, dataset)
   variableFromDataSet = dataset.nfiles;
   fid = fopen...
   ...
   dataset.stream = someDataFromFile;
   ...
   fclose(fid);
   dataset.stuff = 12;
end

This however does not work (i.e. does not fill my objects properties)

I tried to do the following

function dataset = loadABCData(obj, dataset)
...
end

with

function loadData(obj)
  loader = DataLoader;     
  obj = loader.loadABCData(obj);

as well as

function obj = loadData(obj)
  loader = DataLoader;     
  obj = loader.loadABCData(obj);

latter gives me the filled in object in ans but does not assign it to the calling object. I'm new to Matlab OO programming - do however know how things work in other languages. Does anyone of you know how I can implement what I would like to?

Any help is very much appreciated on this. Thank you!

ps. all my classes are handle classes (< handle) pps. the following works, is however not what I aim for (i.e. I want the object to handle the loading itself and do not want to do this at the level where I create the object):

dl = DataLoader; 
ds = DataLoader.loadABCData;