How to pass parameters computed in different functions separately into another function?

Hello,

I have three uicontrol popupmenus and I am supposed to select one item from all popupmenus. Each time I select an item, the appropriate Callback function computes a value (same parameter). After selecting the three items from all three different popupmenus, I press a pushbutton to compute another value (some parameter) which is computed by using the parameters from the previously selected items. here is how it looks like:

 Selection1 = uicontrol('Style','popupmenu',...
                           'String',{'Selection1 ';'Selection2 ';'Selection3'},...
                           'Callback',@Selection1_Callback);

Selection2 = uicontrol('Style','popupmenu',...
                         'String',{'Selection4 ';'Selection5 ';'Selection6'},...
                         'Callback',@Selection2_Callback);

Selection3 = uicontrol('Style','popupmenu',...
                         'String',{'Selection7';'Selection8';'Selection9'},...
                         'Callback',@Selection3_Callback);

 pushbutton = uicontrol('Style', 'pushbutton',...
                       'String', 'Compute', ...
                       'Callback' @pushbutton_Callback);

 edit = uicontrol('Style', 'edit',...
                  'String', '');

 function Selection1_Callback (hObject, eventdata, handles)
 here I compute parameter 1
 end

 function Selection2_Callback (hObject, eventdata, handles)
 here I compute parameter 2
 end

 function Selection3_Callback (hObject, eventdata, handles)
 here I compute parameter 3
 end

 function pushbutton_Callback (hObject, eventdata, handles)
 here I use parameters 1, 2, 3 in order to compute parameter 4
 set(edit, 'String', Parameter4);
 end

So how I can pass parameters 1, 2, and 3 into the pushbutton_Callback function so I could compute parameter 4 and then show it in edit box?

Thank you,

Aleksandar

Answer 1

[Stephen23]

I think that nested functions are the simplest and most intuitive way of passing data between GUI callback functions:

function mainGUI()
...
p1 = [];
p2 = [];
p3 = [];
%
    function Selection1_Callback (hObject, eventdata)
    p1 = ...compute parameter 1
    end
%
    function Selection2_Callback (hObject, eventdata)
    p2 = ...compute parameter 2
    end
%
    function Selection3_Callback (hObject, eventdata)
    p3 = ...compute parameter 3
    end
%
    function pushbutton_Callback (hObject, eventdata)
    p4 = p1 + p2 + p3;
    set(edit, 'String', num2str(p4))
    end
%
end % end of mainGUI function

For other ways of passing data between callback functions you can read the MATLAB documentation:

https://www.mathworks.com/help/matlab/creating_guis/share-data-among-callbacks.html

Note: avoid global and assignin: these will not help you to write good code.

[Aleksandar Petrov]

thank you, it works!!

so the main tip is that the parameters must be declared before they are used in the function