MATLAB - how to use event.eventData, and efficiently - oop

Question

For background information and context for my question, please read this question.
Notice in the updatePlot() method of my DynamicPlotter code, I kind of "reach into" a DynamicDataset property, as follows:
function updatePlot(obj, propNum)
X = get(obj.LH(propNum), 'XData');
Y = get(obj.LH(propNum), 'YData');
X(end+1) = obj.(dynProps{propNum}).newestData(1);
Y(end+1) = obj.(dynProps{propNum}).newestData(2);
set(obj.LH(propNum), 'XData', X, 'YData', Y);
end
updatePlot is a listener callback. Rather than "reach in" to go get the newestData, I am wondering if it would be more efficient to have the data "presented" to the callback with event.eventData. But I am unsure of (a) how to even use event.eventData (the example provided in the documentation isn't very clear to me), and (b) if this yields better or worse performance.
So I guess my main question is, what's the best way for updatePlot() to access the newestData as depicted in the method above: "reaching in and retrieving it" or using event.eventData to "send" the data point to the function to plot?
I hope this wasn't terribly ambiguous.

Answer 1

You first need to have a class that defines an event (in MyClass.m):
classdef MyClass < handle
events
% Event
MyEvent
end
methods
function obj = MyClass
% Constructor
end
end
end
Then you need to create your own EventData subclass (in MyEventData.m):
classdef MyEventData < event.EventData
properties (Access = public)
% Event data
Data
end
methods
function this = MyEventData(data)
% Constructor
this.Data = data;
end
end
end
Attach your data to an instance of the event data class (in a script file):
X = 1:10;
Y = 1:10;
data = struct('XData', X, 'YData', Y);
eventData = MyEventData(data);
And fire the event from your obj and have a listener listen to it:
obj = MyClass;
l = addlistener(obj, 'MyEvent', #(evtSrc,evtData)disp(evtData.Data));
notify(obj, 'MyEvent', eventData)
Anytime you call notify(...), the evtData argument in your listener callback will have your data in its Data property:
>> notify(obj, 'MyEvent', eventData)
XData: [1 2 3 4 5 6 7 8 9 10]
YData: [1 2 3 4 5 6 7 8 9 10]