MATLAB: Non-Handle Classes with events and listeners

classeseventslistenersMATLAB

I do think I know the answer to this but would like to clarify in case I missed anything.

Is it only handle classes that can implement events and listeners? From the documentation I read, it seems that handle classes inherit the 'notify' and 'addlistener' methods.

So if my understanding is correct then value classes can never define events or notify listeners?

Regards, Phil

Best Answer

For the sake of completeness I will answer the question myself.

There is no direct way of using 'notify' and 'addlistener' without the class being a handle class. To use the official matlab Events and Listeners you must ensure that your class is a handle class.

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MATLAB: Using multiple Event Listener

I think the listeners you create with add_exec_event_listener are similar to the listeners you create with addlistener in MATLAB. I think you want the equvilent of the listeners you get with event.listener in MATLAB. The difference being that the listener h that you are creating gets deleted when you overwrite h, but adding your second listener. I think you need to make h an array

h(1) = add_exec_event_listener(blk_SpO2, event, listener);
h(2) = add_exec_event_listener(blk_BD, event, listener);

MATLAB: Create an empty array of class event.listener

You can create empty objects with the static empty() method of a class, as documented at http://www.mathworks.com/help/techdoc/matlab_oop/brd4btr.html. In this case using "event.listener.empty" as the initial value for the hListener property should work:

properties
    hListenerArray = event.listener.empty;
end

An additional comment: if you use the event.listener constructor to create the listeners instead of using addlistener then you will not have to write a delete method because you will have the only reference to them in hListenerArray and they will simply go out of scope and delete themselves when obj is deleted. addlistener is adding an extra reference to the object being listened to and you do not want that in this case.

obj.hListenerArray(end+1) = event.listener(listenObj, listenEvent, callbackFcn);

Best Answer

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MATLAB: Using multiple Event Listener

MATLAB: Create an empty array of class event.listener

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