How to pass variable to function handle using registerevent?

I'm streaming data from another peice of software and I'm having matlab read events from the software and if and event occurs I call my function. The funciton handler requires me to specifcy which channel the event will occur, but I'm not clear on the syntact I should use to specificy.

Below is what I have, where I need some variables to pass into 'OnEventDataArrived"

global gLCDoc
gLCDoc.registerevent({'OnEventDataArrived' @app.MyFunction})

Does anyone have any ideas?

Answer 1

[Hari]

Hi Dc215905,

I understand that you are streaming data from another software and want to read events in MATLAB. When an event occurs, you are calling a function that requires you to specify which channel the event will occur, and you want to know how to pass variables to a function handle using the “registerevent” function in MATLAB.

To pass variables to the function handle using “registerevent”, you can use an anonymous function. Here's an example:

% Create an instance of the sample class
gLCDoc = SampleClass();

% Register the event and pass variables to the function handle
channel = 2; % Specify the channel you want to pass as a variable
eventData = struct(); c
gLCDoc.registerevent(eventData, @(src, event) MyFunction(src, event, channel)); % Register event is specified using anonymous function.

You can define a custom function to handle when the specific event is triggered.

function MyFunction(src, event, channel)
disp(['Event occurred on channel ' num2str(channel)]);
disp('Performing event handling...');
% Add your event handling code here
end

Here is the custom class to handle the events.

% Create a custom event data class
classdef MyEventData < event.EventData 
    properties   
        eventData      
    end   
    methods     
        function obj = MyEventData(eventData)       
            obj.eventData = eventData;      
        end  
    end
end

% Create a sample handle class
classdef SampleClass < handle
    events
        OnEventDataArrived
    end    
    methods 
        function registerevent(obj, eventData, functionHandle)
            notify(obj, 'OnEventDataArrived', MyEventData(eventData));
            obj.addlistener('OnEventDataArrived', functionHandle);
        end
    end
end

You can simulate the behaviour using “notify” function by virtually triggering the event.

% Simulate an event occurrence
notify(gLCDoc, 'OnEventDataArrived');

Here is the output observed:

Event occurred on channel 2
Performing event handling...

By doing this way you can trigger an event by passing arguments to the custom function and handle the event triggering workflow.

Refer to the MATLAB documentation for Anonymous Functions to learn more about creating anonymous functions in MATLAB.

https://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

For more information on the “registerevent” method, you can refer to the MATLAB documentation on event notification and handling.

https://www.mathworks.com/help/matlab/ref/registerevent.html

Hope this helps!