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Leon
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How to initiate an existing callback from a current callback in Matlab app-designer?

Asked by Leon
on 8 Sep 2019
Latest activity Commented on by Hope Q
on 25 Oct 2019 at 22:15
In the below example, what I'm trying to achieve is to call back the 2nd function from the first callback function. How do I do that?
First callback
function NextButtonPushed(app, event)
app.StationNo.Value = app.StationNo.Value + 1;
callback to the bleow function
end
2nd callback
function PlotstationButtonPushed(app, event)
% ---Station No ---
b = app.StationNo.Value; % get the station no
% --- load the file ---
File1 = ['stations/', app.FileName.Value];
load (File1); % values are stored as 'Sta'
...
...
end

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R2019a

1 Answer

Answer by Cris LaPierre
on 9 Sep 2019
 Accepted Answer

callbacks are just functions. Call them using app.<callback name>. Just set the inputs correctly.
function NextButtonPushed(app, event)
app.StationNo.Value = app.StationNo.Value + 1;
% callback to the bleow function
app.PlotstationButtonPushed(app, event)
end

  2 Comments

It works! Thank you so much.
The only change I need to make is to remove the contents inside the parenthesis and change it to
app.PlotstationButtonPushed
I have a pesonal best practice of "don't call a callback from a callback". Instead, write a function that performs the task and call that function from both callbacks, as needed
I haven't run into issues in App Designer (yet - I'm just learning) but I've seen issues arise in GUIDE projects if a developer loses track of the handles structure and the hObject that invoked the callback.
In GUIDE the function called from either callback would pass and return the handles structure. The hObject was preserved in the original callback so that handles was updated with guidata at the end of the callback.
handles = PerformTask(handles);
guidata(hObject, handles);
In App Designer the function could be defined as a private method and called from either callback.
app.PerformTask();.

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