CODEWITHSUNDEEP
matlabevent-listener
rlbond
rlbond

Reputation: 67739

MATLAB nested event notifications?

It seems MATLAB handles will not respond to more than one notification from the same source at a time. Unfortunately this is a big problem for me. Here's an example of what I'm talking about:

classdef testClass < handle
    events
        testevent
    end

    methods
        function obj = testClass
            obj.addlistener('testevent', @obj.respond);
        end
        function raise(obj)
            obj.notify('testevent');
        end
        function respond(obj, varargin)
            fprintf('Responded!\n');
            obj.raise();
        end
    end

end

when I execute the code

c = testClass;
c.raise();

The result is

Responded!

But I really want the recursion to work, though obviously in this simple example it would recurse infinitely. Is there any way to get this behavior?

Upvotes: 2

Views: 511

Answers (1)

Dang Khoa
Dang Khoa

Reputation: 5823

You can make the listener recursive by setting the listener handle's Recursive property to true. Listener handle properties are in the event.listener help page. You just need to specify an output argument to obj.addlistener to retrieve the handle.

Here's the code I used to make it work:

classdef testClass < handle
    events
        testevent
    end

    methods
        function obj = testClass
            lh = obj.addlistener('testevent', @obj.respond);
            lh.Recursive = true;
        end
        function raise(obj)
            notify(obj,'testevent');
        end
        function respond(obj, varargin)
            fprintf('Responded!\n');
            obj.raise();
        end
    end
end

Also note that there is a default recursion limit of 500 calls, so naively the code won't infinitely recur; use set(0, 'RecursionLimit', N) to change that. I would think setting N=inf is a bad idea.

Upvotes: 4

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