[Tkinter] tkinter freezes by clicking button

[Gribouillis]

This is very nice. I had some problems with the paths to the files, because I'm a linux user, so here are a few changes to handle the paths in a platform-independent way. First I change saveSudoku() to

    def saveSUDOKU(self):
       CHECK = self.checkSUDOKU(self.solution)
       if CHECK[0] and CHECK[1]:    # check if Sudoku is valid and complete
           filecount = 1    # variable for how many sudoku files are already existing
           while os.path.isfile(self.path_to("sudoku%s.txt" % filecount)):
               filecount += 1
           sudokuFile = open(self.path_to("sudoku%s.txt" % filecount), 'w')
           solutionFile = open(self.path_to("solution%s.txt" % filecount), 'w')
           # ----- create textfiles for sudoku and the solution ----- #
           for row in range(9):
               for col in range(9):
                   sudokuFile.write(self.sudoku[row][col])
                   solutionFile.write(self.solution[row][col])
               sudokuFile.write('\n')
               solutionFile.write('\n')
           sudokuFile.close()
           solutionFile.close()
           self.message_txt.set('Files saved...')
       else:
           self.message_txt.set('Sudoku must be valid and complete!')

Then at the beginning of the SudokuSolver class

    def __init__(self, parent):
        Frame.__init__(self, parent, name='frame')
        self.parent = parent
        self.initUI()
        self.blankSUDOKU()
        self.sudokudir = os.path.join(os.getcwd(), 'sudokus')
        
    def path_to(self, name):
        return os.path.join(self.sudokudir, name)

You also need to change one line in initSUDOKU()

            sudokuFile = open(self.path_to("sudoku%s.txt" % (randint(1, L))))

The print button does not work, you need to change the callback for this.

I suggest to change SudokuSolver_main like so

# SudokuSolver_main.py
if __name__ == '__main__':
    from tkinter import Tk
    import SudokuSolver_class as Sudokuolver

    def main():
        root = Tk()
        app = Sudokuolver.SudokuSolver(root)
        root.mainloop()
 
    main()

because the child process does not need to import tkinter at all.