Set class method as CloseRequestFcn

I am currently working on a waitbar that is implemented as a class. I need to detect when the user clicks the X-button of the window to cancel computations and then set a flag.

Considering the following class:

classdef myWaitbar < handle

    properties
      figHandle
      cancel
    end

    methods

      function obj = myWaitbar()
        obj.cancel = false;
        obj.figHandle = figure('CloseRequestFcn', @...);
      end

      function setFlag(obj)
        obj.cancel = true;
      end

    end
end

Does anybody know how to declare CloseRequestFcn and setFlag to make this work? I tried a few different approaches but could not find a proper way.

Thank you

Answer 1

[Geoff Hayes]

Sebastian - you can try the following

 function obj = myWaitbar()
     obj.cancel = false;
     obj.figHandle = figure('CloseRequestFcn', @(h,e)obj.setFlag);
 end
 function setFlag(hObject,eventdata)
     hObject.cancel = true;
     delete(hObject.figHandle);
 end

The setFlag method will be called when the x is pressed in the corner of the wait bar figure. (At least it does for me when using R2014a.) I'm not sure how you will report the change to cancel though. Do you have "something" listening or waiting for it to change value?

[Guillaume]

Hum, I believe the anonymous function should be:

@(h,e) obj.setFlag(e)
%or
@(~, e) obj.setFlag(e)

As it is you'll get a not enough input arguments error in setFlag.

And I find calling hObject the first argument of setFlag misleading as it seems to implies it's the h of the @(h,e) whereas it's actually the obj of obj.setFlag, so I'd have:

function setFlag(obj, eventdata)
    obj.cancel = true;
    delete(obj.fighandle);
end

Or to make everything even clearer:

function obj = myWaitbar()
     obj.cancel = false;
     obj.figHandle = figure('CloseRequestFcn', @(h,e)obj.setFlag(h, e));
end
function setFlag(obj, hsource, eventdata)  %eventdata could be replaced by ~
     obj.cancel = true;
     delete(hsource);
 end

Third option is:

function obj = myWaitbar()
     obj.cancel = false;
     obj.figHandle = figure('CloseRequestFcn', @(~,~)obj.setFlag);
end
function setFlag(obj)
     obj.cancel = true;
     delete(obj.figHandle);
end

[Sebastian]

Geoff Hayes and Guillaume, thank you for your efforts. I kept trying and finally found a solution that works for me in R2016b:

...
obj.figHandle = figure('CloseRequestFcn', @obj.figureCloseFcn);
...
function figureCloseFcn( obj, src, evt )
...

I am not really sure why this works but I think that src and evt are passed by default to a CloseRequestFcn so it is redundant to add them to the function handle or it even causes errors. I listen for cancel in the main loop to open a questdlg.