Why doesn't Matlab know the variable from appdesigner despite it is globalized into matlab workspace ?

Hi All

I have written an app that using a pushbutton receives the working directory folder adress from the user and changes the matlab wd to that. the other push button is to run an mfile in thatdirectory and then cd() to some subfolder.

Despite I see the global variable shared between app and workspace ,it seems that matlab can not use it and therefore the cd() does not work cause the variable is seen as empty despite it's not

here is the app code :

properties (Access = public)
        %selectedPath: path selected by user in ButtonPushed function
        selectedPath= 'C:\' % Description
        
    end


    methods (Access = private)

        % Button pushed function: ChooseDirectoryButton
        function ChooseDirectoryButtonPushed(app, event)
            global currentFolder
            app.selectedPath = uigetdir();
            app.UIFigure.Visible = 'on'; 
            currentFolder=app.selectedPath;
            cd(currentFolder)
        end

        % Button pushed function: ExecuteButton
        function ExecuteButtonPushed(app, event)
            global currentFolder;
            currentFolder=app.selectedPath;
            assignin('base','currentFolder',currentFolder);
            goFolder = strcat(currentFolder,'\Fsolver.m');
            run(goFolder)
            app.UIFigure.Visible = 'on';
            
        end
        end
        

and the first lines of the mfile :

global currentFolder
inputs =strcat(currentFolder,'\Input')
cd(inputs)

these are the errors :

Error using cd
Cannot CD to \Input (Name is nonexistent or not a directory).

Error in mysolver (line 37)
cd(inputs)

Error in run (line 91)
evalin('caller', strcat(script, ';'));

Error in apprivate/ExecuteButtonPushed (line 39)
            run(goFolder)
 
Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 309)
Error while evaluating Button PrivateButtonPushedFcn.

[farzad]

ok , it seems that it's the

assignin('base','currentFolder',currentFolder);

line that send the variable to matlab workspace, but still ,when the Mfile runs, it can not read it. I think it's a matter of time and velocity of execution.

should I use uiwait ? is it relevant ?

[farzad]

if I remove the line

global currentFolder

from the MFile, then Matlab does not even know the variable at all. if I do, then it knows currentFolder only as an empty variable , even despite I have used assignin

Undefined function or variable 'currentFolder'.

[farzad]

this sounds like my problem , but I am not using a function , but only running an mfile from an app

https://www.mathworks.com/matlabcentral/answers/405959-why-doesn-t-matlab-recognize-the-variable-i-have-assigned-in-a-script-called-from-a-function

[farzad]

could someone help ?

Answer 1

[Geoff Hayes]

farzad - rather than using a global variable, can't you just use pwd to identify the current working directory? So the code in your m file would then become

inputPath = fullfile(pwd, 'Input')
cd(inputPath)

where fullfile is used to build the path. Of course the problem here is on the next line you will changed directory to that folder. Is that necessary? Could you just use inputPath for any code that tries to read or write to file?

[farzad]

Thank you so much !! that beautifully worked !!

Shall you please kindly check my other question that is more challenging now for me ?

https://www.mathworks.com/matlabcentral/answers/511724-will-an-app-run-an-mfile-after-cmpiling-if-working-directory-is-not-the-exe-installation-directory

I would be so thankfull !!