MATLAB Answers

Matt J
0

addlistener syntax not recognized in R2014b

Asked by Matt J
on 18 Nov 2014
Latest activity Answered by Ian Noell on 27 Nov 2014
I've just installed R2014b, and have been testing various pieces of my code library fearful of what the new Graphics System is going to break. One routine I have relies on a File Exchange submission with the following local function,
function localSetupPositionListener(hFig,imAxes)
% helper function to sets up listeners for resizing, so we can detect if
% we would need to change the fontsize
PostPositionListener = handle.listener(hFig,'ResizeEvent',...
{@localPostPositionListener,imAxes});
setappdata(hFig,'KenFigResizeListeners',PostPositionListener);
end
After running the MATLAB Graphics Updater app, this local function gets converted to the following,
function localSetupPositionListener(hFig,imAxes)
% helper function to sets up listeners for resizing, so we can detect if
% we would need to change the fontsize
PostPositionListener = addlistener(hFig,'SizeChanged',...
{@localPostPositionListener,imAxes});
setappdata(hFig,'KenFigResizeListeners',PostPositionListener);
end
But when I run the code, the line that has changed throws an error,
No method 'addlistener' with matching signature found for class 'matlab.ui.Figure'.
Error in TextZoomable>localSetupPositionListener (line 80)
PostPositionListener = addlistener(hFig,'SizeChanged',...
Error in TextZoomable (line 58)
localSetupPositionListener(hFig,hAx);
Any ideas why the error occurs and, as importantly, why the app doesn't catch it (so I can be on the lookout for other instances where it may fail)?

  2 Comments

Silly question: have you tried just reverting it to the previous if it was changed by the updater app?
I am on R2014a at home and addlistener does not work with that syntax there, but the top version does (well, I can type the listener line without a syntax error, I haven't tried hooking it up somewhere live.
Adam, yes I verified that the original version does not work in R2014b.

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3 Answers

Answer by matt dash
on 18 Nov 2014
 Accepted Answer

Addlistener doesn't let you use the cell array syntax on the 3rd argument the way every other callback function works. You must specify a "bare" function handle for the 3rd argument.

  1 Comment

Thanks.
You must specify a "bare" function handle for the 3rd argument.
I think you mean it needs to be changed as follows?
PostPositionListener = addlistener(hFig,'SizeChanged',...
@(o,e) localPostPositionListener(o,e,imAxes) );

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Answer by Ian Noell on 27 Nov 2014

As matt dash said, addlistener needs a function handle or an anonymous function for the callback. The cell array syntax was supported by handle.listener (although undocumented) but is not for event.listener/addlistener.
I have added a note to the message in the MATLAB Graphics Updater app and updated the submission. You will need to make manual changes to your code to update the callback.

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Answer by Guillaume
on 18 Nov 2014

Which version are you upgrading from?
Your old code gives me the same error in R2013b. The problem in either version is that addlistener / event.listener expects a function handle for the third argument, whereas you're passing a cell array, the purpose of which I'm not sure.

  1 Comment

Can't account for that, I'm afraid. The original version works fine for me in R2013b.

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