How to run functions in GUI opening function and pass variables?

Hi !

I would like to do the following (not sure if it is possible) :

I would like to create a GUI and in the GUI_OpeningFcn

function GUI_OpeningFcn(hObject, eventdata, handles, varargin)

% 1- call Variables Initialization Function --> output: all variable that will not change (a lot!)

% 2- wait for push button to take the value from a slider

% 3- pass output from 1 & 2 to a function with the previous output of this function 

% 4- plot output 

% 5- go back to step 2

Since passing variables between function in the GUI is diffrent from the normal script. Is it possible to do it this way ?

Thanks !