How can I write .NET event in C# and attach a matlab callabk to them

Hi,

I'm working on a project that involves code written in C# and matlab. On the C# side I've declared an event using the standard signature of an Event Handler Delegate as explained in http://www.mathworks.com/help/matlab/matlab_external/working-with-net-events-in-matlab.html I did verify that the event indeed fires (and can be handled from another C# class).

However, ater registering a matlab listener (using the addlistener(obj,<eventName>,<calbbackName>) method), when the event fires, the matlab callback is not triggered.

As I have no problems registering matlab callbacks to other .NET events, I must conclude that somehow I'm using wrong syntax in my C# code.

Can someone please point me to a generic example of C# code that implements an event in a way that Matlab can listen to?

Answer 1

[Markus Leuthold]

Hi Amir

the handling of .NET events in Matlab is indeed really strange. They are only fired under certain conditions, which don't make any sense to me. An example: Assume you have a winform called Form1 with a combobox called comboBox1 on it. You want a Matlab listener which acts on a change of the combobox selection

 classdef TestEvents < handle
    properties
        f
    end

    methods
        function self=TestEvents
            asm=NET.addAssembly('C:\...\test_events.exe');
            self.f=test_events.Form1;
            self.f.Show;
            self.f.Activate;
        end

        function r=setListener(self)
            r=addlistener(self.f.comboBox1,'SelectedValueChanged',@self.myListener);
        end

        function myListener(self,src,event)
            disp('event fired')
        end
    end
 end

Now you show the winform and set the listener by calling

t=TestEvents;
t.setListener;

nothing happens on firing 'SelectedValueChanged'. However, if you call

t=TestEvents;
a=t.setListener;

then the listener is called correctly. So it seems like you need the result of addlistener in the current context, otherwise the event is not handled. This sounds like a bug to me, and I'd like to hear from Mathworks some more details about this behavior. This is on Matlab 2012a

best regards, Kusi