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Need to test the validity of an application handle

17 vues (au cours des 30 derniers jours)
Richard
Richard le 23 Mar 2023
Modifié(e) : Adam Danz le 24 Mar 2023
I call a data application from my main application and store the data app handle in a main app local variable.. The data app has a Close button which first sets the handle to [] (by using the callingApp handle and then deletes itself. This works fine, no problem.
The probem occurs when the user closes the data app window using the "X" in the upper r/h corner. This action does execute the delete callback, but I'm unable to add code to this callback to also empty the data app handle. I'd prefer the user not use the "X", but it's impossible to prevent him from doing so inadvertently.
Isvalid would do the trick, but it's not available in 2022b. I could upgrade to 2023a, but I'd prefer not doing so at this time. An solutions?

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Adam Danz
Adam Danz le 23 Mar 2023
Modifié(e) : Adam Danz le 24 Mar 2023
> I'd prefer the user not use the "X", but it's impossible to prevent him from doing so inadvertently.
You can set the [x] close button to be unresponsive to clicks.
uif = uifigure('CloseRequestFcn',[])
Or display an alert box to inform the user to use the app's close button
uif = uifigure('CloseRequestFcn',@(f,~)uialert(f,'Use the app''s close button','No-Can-Do'))
To close these figures
close(uif,'force')
% or
delete(uif)
or, if you lose the handle, this deletes all figures
close all force
  1 commentaire
Richard
Richard le 24 Mar 2023
I thought there might be a callback for the "X", but wasn't able to find it. That will do the trick.

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Walter Roberson
Walter Roberson le 24 Mar 2023
Isvalid would do the trick, but it's not available in 2022b.
isvalid with lower-case I has been available since at least 2006.
  2 commentaires
Richard
Richard le 24 Mar 2023
Modifié(e) : Richard le 24 Mar 2023
I can't look at the code from this computer, but I know I've tried lower case without succes. I didn't realize there was an upper case function elsewhere in the various toolboxes. The "Isvalid" in my original question is only capitalized due to force of habit.
Below is the error I receive in 2022B with the correct lower case.
'isvalid' requires one of the following:
Industrial Communication Toolbox
Image Acquisition Toolbox
Instrument Control Toolbox
Error in W3DPlot/UIAxesButtonDown (line 668)
if ~isvalid(app.hWdataPoint)
Error in matlab.apps.AppBase>@(source,event)executeCallback(ams,app,callback,requiresEventData,event) (line 62)
newCallback = @(source, event)executeCallback(ams, ...
Error while evaluating UIAxes ButtonDownFcn.
Walter Roberson
Walter Roberson le 24 Mar 2023
I am running R2022b. isvalid() exists in a large number of methods, including handle class; https://www.mathworks.com/help/matlab/ref/handle.isvalid.html
If it is telling you that you need one of those toolboxes, we might guess that whatever app.hWdataPoint is is not a handle. What shows up for class(app.hWdataPoint) at that point ? And ishandle(app.hWdataPoint) and isa(app.hWdataPoint, 'handle') ?

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