Python Tkinter 2 classes
<p>I have 2 classes, i create the instance of each class like this </p>

<pre><code>if __name__ == '__main__':
    root = Tk()
    w, h = root.winfo_screenwidth(), root.winfo_screenheight()
    root.focus_set() # &lt;-- move focus to this widget
    root.geometry("%dx%d+0+0" % (w, h))
    root.title("Circus ticketing system")

    UI_Class = GUI(root)
    Program_Class = Program()

    root.mainloop()
</code></pre>

<p>i set variables in GUI like this:</p>

<pre><code>self.tenAmShowBtn = Button(self.fMain,text='10am Show',command=Program_Class.tenAmShow)
        self.tenAmShowBtn.grid(column=0,row=2)
</code></pre>

<p>and to access variables in (ex)GUI from Program i do like this: </p>

<pre><code>UI_Class.tenAmShowBtn.config(bg='#00f0ff')
</code></pre>

<p>but i keep getting errors like <code>NameError: name 'UI_Class' is not defined</code>
and <code>NameError: name 'Program_Class' is not defined</code>
and <code>AttributeError: 'GUI' object has no attribute 'tenAmShowBtn'</code>i don't understand how the hell do i do this, the Program class continuosly has to access the GUI and edit variables and widgets, but i can't access variables, keep getting error after error, it woks great when i put everything in 1 class, i just CAN'T get this to work with 2 separete classes.</p>

<p>I put the whole code because i cannot explain in just bits of code, i aplogise.</p>

<pre><code>try:
    # for Python2
    from Tkinter import *
except ImportError:
    # for Python3
    from tkinter import *
from random import randint
#from user import Program
class GUI:
    def __init__(self, parent):
        self.seats_being_bought1 = IntVar()#Light-Blue buttons number for textvariable
        self.seats_being_bought1.set(0)
        self.seats_being_bought2 = IntVar()#Light-Blue buttons number for textvariable
        self.seats_being_bought2.set(0)
        self.seats_being_bought3 = IntVar()#Light-Blue buttons number for textvariable
        self.seats_being_bought3.set(0)
        self.available_seats1 = IntVar() #Non-red buttons
        self.available_seats1.set("0")
        self.available_seats2 = IntVar() #Non-red buttons
        self.available_seats2.set(0)
        self.available_seats3 = IntVar() #Non-red buttons
        self.available_seats3.set(0)
        self.pricePerTicket1 = IntVar()
        self.pricePerTicket1.set(5)
        self.pricePerTicket2 = IntVar()#&lt;&gt; Ticket/Seat Price Variables
        self.pricePerTicket2.set(5)
        self.pricePerTicket3 = IntVar()
        self.pricePerTicket3.set(12)
        self.totalPrice1 = IntVar()
        self.totalPrice1.set(0)
        self.totalPrice2 = IntVar()#total price variables
        self.totalPrice2.set(0)
        self.totalPrice3 = IntVar()
        self.totalPrice3.set(0)
        self.totalTicketsSold = IntVar()#Total seats sold
        self.totalTicketsSold.set(0)
        self.totalIncome = IntVar()#Total income
        self.totalIncome.set(0)
        self.white = '#ffffff' #save time
        self.currentShow = StringVar()#currrent show
        self.instructions_text = 'Select the show you desire, then click one of the seats to the right and click the buy button'
        self.button_list1={} #all seats(Buttons)as matrix/object
        self.button_list2={}
        self.button_list3={}
        self.total_seats1 = StringVar()
        self.total_seats2 = StringVar()
        self.total_seats3 = StringVar()
        self.total_seats1.set('/250')
        self.total_seats2.set('/150')
        self.total_seats3.set('/150')
        self.selected_button_list1=[] #Light-Blue buttons
        self.selected_button_list2=[] #Light-Blue buttons
        self.selected_button_list3=[] #Light-Blue buttons
        self.previousTransactionButtonList1 = []#List of Seats in the last transaction
        self.previousTransactionButtonList2 = []
        self.previousTransactionButtonList3 = []
        self.automatic_seat_selection_no = IntVar()#automatic seat selection number
        self.automatic_seat_selection_no.set(0)
        self.f1 = Frame(parent) #Frame for Seats/Buttons
        self.seatTitle = Label(self.f1,bg=self.white,textvariable=self.currentShow).grid(row=0,column=0,columnspan=11,sticky=E+W)
        self.f1.grid(column=2,row=0)
        self.f2 = Frame(parent) #Frame for Seats/Buttons
        self.seatTitle = Label(self.f2,bg=self.white,textvariable=self.currentShow).grid(row=0,column=0,columnspan=11,sticky=E+W)
        self.f2.grid(column=2,row=0)
        self.f3 = Frame(parent) #Frame for Seats/Buttons
        self.seatTitle = Label(self.f3,bg=self.white,textvariable=self.currentShow).grid(row=0,column=0,columnspan=11,sticky=E+W)
        self.f3.grid(column=2,row=0)

        self.f2.grid_remove() #Hide other 2 frames
        self.f3.grid_remove() #Hide other 2 frames

        #self.create_UI(parent)
        #START WITH 10AM SHOW
        #self.currentShow.set('10Am Show')
        #self.tenAmShowBtn.config(bg='#00f0ff')
        Program.tenAmShow(Program)
        Program.displaySeats(10)#10 refers to 10am show
        #CREATING OTHER SEATS BUT THEIR FRAMES ARE HIDDEN
        Program.displaySeats(3)
        Program.displaySeats(8)

    def create_UI(self,parent):
        self.fMain = Frame(parent)#Frame for rest of program

        fLegend = Frame(self.fMain)#Frame for Legend
        legendLabel = Label(fLegend,text='Legend').grid(column=0,row=0,columnspan=3,sticky=E+W)
        legendRed = Label(fLegend,text='seat123',fg='#ff0000',bg='#ff0000').grid(column=0,row=1,sticky=E+W)
        legendRed1 = Label(fLegend,text=' =').grid(column=1,row=1)
        legendRed2 = Label(fLegend,text='Taken Seat').grid(column=2,row=1)
        legendLightRed = Label(fLegend,text='seat123',fg='#f99999',bg='#f99999').grid(column=0,row=2,sticky=E+W)
        legendLightRed1 = Label(fLegend,text=' =').grid(column=1,row=2)
        legendLightRed2 = Label(fLegend,text='Bought Seat').grid(column=2,row=2)
        legendLightBlue = Label(fLegend,text='seat123',fg='#00f0ff',bg='#00f0ff').grid(column=0,row=3,sticky=E+W)
        legendLightBlue1 = Label(fLegend,text=' =').grid(column=1,row=3)
        legendLightBlue2 = Label(fLegend,text='Selected Seat').grid(column=2,row=3)
        fLegend.grid(column=0,row=0,columnspan=3)
        #end Legend frame
        self.instructions = Label(self.fMain, text=self.instructions_text).grid(column=0,row=1,columnspan=3)
        #Show Selection gui
        self.tenAmShowBtn = Button(self.fMain,text='10am Show',command=Program_Class.tenAmShow)
        self.tenAmShowBtn.grid(column=0,row=2)
        self.threePmShowBtn = Button(self.fMain,text='3pm Show',command=Program_Class.threePmShow)
        self.threePmShowBtn.grid(column=1,row=2)
        self.eightPmShowBtn = Button(self.fMain,text='8Pm Show',command=Program_Class.eightPmShow)
        self.eightPmShowBtn.grid(column=2,row=2)
        #Purchase details and commands gui
        self.seat_amountLabel = Label(self.fMain, text='Amount of seats Available').grid(column=0, row=3)
        self.seat_amountEntry = Label(self.fMain, textvariable=self.available_seats1,bg="#444444",fg='#ffffff',anchor=E)
        self.seat_amountEntry.grid(column=1,row=3,sticky=E+W)
        self.seat_amountTotal = Label(self.fMain,textvariable=self.total_seats1 ,bg='#444444',fg='#ffffff',anchor=W)
        self.seat_amountTotal.grid(column=2,row=3,sticky=E+W)
        self.seatsBeingBoughtLabel = Label(self.fMain,text='Amount of seats being purchased').grid(column=0,row=4)
        self.seatsBeingBoughtVal = Label(self.fMain, textvariable=self.seats_being_bought1,bg="#444444",fg='#ffffff')
        self.seatsBeingBoughtVal.grid(column=1,row=4,columnspan=2,sticky=E+W)
        #price per ticket
        self.pricePerTicketLabel = Label(self.fMain,text='Cost per Ticket/Seat in $').grid(column=0,row=5)
        self.pricePerTicketVal = Label(self.fMain,textvariable=self.pricePerTicket1,bg='#ffffff',fg='#444444')
        self.pricePerTicketVal.grid(column=1,row=5,columnspan=2,sticky=E+W)
        #total price
        self.totalPriceLabel = Label(self.fMain,text='Total Price in $').grid(column=0,row=6)
        self.totalPriceVal = Label(self.fMain,textvariable=self.totalPrice1,bg='#ffffff',fg='#444444')
        self.totalPriceVal.grid(column=1,row=6,columnspan=2,sticky=E+W)
        #Automatically select seats
        self.auto_seat_selection_label = Label(self.fMain,text='Amount of seats to buy:').grid(column=0,row=7)
        self.auto_seat_selection_entry = Entry(self.fMain, textvariable=self.automatic_seat_selection_no).grid(column=1,row=7,columnspan=2,sticky=E+W)
        #cancel and purchase button
        self.resetBtn = Button(self.fMain,text="Cancel/Reset",bg='#ff0000',command=Program_Class.CancelTransaction).grid(column=0,row=8,columnspan=1,sticky=E+W)
        self.buyTicketsBtn = Button(self.fMain,text="Buy ticket",bg='#00f0ff',command=Program_Class.click_function).grid(column=1,row=8,columnspan=2,sticky=E+W)
        #totals
        self.totalTicketsSoldLabel = Label(self.fMain,text='Total tickets sold:').grid(column=0,row=9)
        self.totalTicketsSoldVal = Label(self.fMain,textvariable=self.totalTicketsSold).grid(column=1,row=9,columnspan=2)
        self.totalIncomeLabel = Label(self.fMain,text='Total Income for the Day in $:').grid(column=0,row=10)
        self.totalIncomeVal = Label(self.fMain,textvariable=self.totalIncome).grid(column=1,row=10,columnspan=2)

        self.fMain.grid(column=1,row=0,sticky=N)     

class Program:
    def __init__(self):
        print('test')
    def click_function(self): #Buy Button click
        show = self.currentShow.get()
        action = 0
        inputed_seat = self.automatic_seat_selection_no.get()
        #for automatic seat selection
        if(inputed_seat != 0):
            if(show == '10Am Show'):
                button_list = self.button_list1
                available_seats = self.available_seats1.get()
            elif(show == '3Pm Show'):
                button_list = self.button_list2
                available_seats = self.available_seats2.get()
            else:
                button_list = self.button_list3
                available_seats = self.available_seats3.get()

            counter_var = 1
            seat = 1
            while counter_var &lt;= inputed_seat:#i use while loop instead of for loop so i can continue/extend the loop if i find a taken/red seat
                if(inputed_seat &gt; available_seats):
                    print('Not enough seats available')
                    break
                else:
                    if seat in button_list:
                        if(button_list[seat]['bg'] != '#f99999' and button_list[seat]['bg'] != '#00f0ff'):
                            self.SeatClick(seat)
                        else:
                            counter_var -= 1
                    else:#seat is taken/red
                        if(available_seats == 0):
                            print('Not enough seats available')
                            break
                        else:
                            counter_var -= 1
                    counter_var += 1
                    seat += 1
                self.automatic_seat_selection_no.set(0)
            self.click_function()

        else:#for manual seat selection
            if(show == '10Am Show'):
                action = len(self.selected_button_list1)
            elif(show == '3Pm Show'):
                action = len(self.selected_button_list2)
            else:
                action = len(self.selected_button_list3)
            if(action != 0):
                if(show == '10Am Show'):
                    del self.previousTransactionButtonList1[:]#Clear last transaction
                    for i in range(len(self.selected_button_list1)):
                        self.button_list1[self.selected_button_list1[i]].config(bg='#f99999')
                        self.available_seats1.set(self.available_seats1.get() - 1)
                        #save to previous transactions
                        self.previousTransactionButtonList1.append(self.button_list1[self.selected_button_list1[i]])
                    self.selected_button_list1 = []
                    self.seats_being_bought1.set(0)
                    self.totalPrice1.set(0)
                elif(show == '3Pm Show'):
                    del self.previousTransactionButtonList2[:]#Clear last transaction
                    for i in range(len(self.selected_button_list2)):
                        self.button_list2[self.selected_button_list2[i]].config(bg='#f99999')
                        self.available_seats2.set(self.available_seats2.get() - 1)
                        #save to previous transactions
                        self.previousTransactionButtonList2.append(self.button_list2[self.selected_button_list2[i]])
                    self.selected_button_list2 = []
                    self.seats_being_bought2.set(0)
                    self.totalPrice2.set(0)
                else:
                    del self.previousTransactionButtonList3[:]#Clear last transaction
                    for i in range(len(self.selected_button_list3)):
                        self.button_list3[self.selected_button_list3[i]].config(bg='#f99999')
                        self.available_seats3.set(self.available_seats3.get() - 1)
                        #save to previous transactions
                        self.previousTransactionButtonList3.append(self.button_list3[self.selected_button_list3[i]])
                    self.selected_button_list3 = []
                    self.seats_being_bought3.set(0)
                    self.totalPrice3.set(0)
                #get total seats sold INITIAL ONLY, SPECIFIC FUNCTION AT END OF PROGRAM
                self.resetVal()
            else:
                print('No Seats Selected!')

    def CancelTransaction(self):
        show = self.currentShow.get()
        if(show == '10Am Show' and len(self.previousTransactionButtonList1) &gt;= 1):
            for x in range(len(self.previousTransactionButtonList1)):
                self.previousTransactionButtonList1[x].config(bg='SystemButtonFace')#make button return to available color
                self.available_seats1.set(self.available_seats1.get() + 1)#Adjust available seat counter
                self.totalTicketsSold.set(self.totalTicketsSold.get() - 1)
            self.resetVal()
            del self.previousTransactionButtonList1[:]#delete/clear previous transaction
        elif(show == '3Pm Show' and len(self.previousTransactionButtonList2) &gt;= 1):
            for x in range(len(self.previousTransactionButtonList2)):
                self.previousTransactionButtonList2[x].config(bg='SystemButtonFace')
                self.available_seats2.set(self.available_seats2.get() + 1)#Adjust available seat counter
                self.totalTicketsSold.set(self.totalTicketsSold.get() - 1)
            self.resetVal()
            del self.previousTransactionButtonList2[:]#delete/clear previous transaction
        elif(show == '8Pm Show' and len(self.previousTransactionButtonList3) &gt;= 1):
            for x in range(len(self.previousTransactionButtonList3)):
                self.previousTransactionButtonList3[x].config(bg='SystemButtonFace')
                self.available_seats3.set(self.available_seats3.get() + 1)#Adjust available seat counter
                self.totalTicketsSold.set(self.totalTicketsSold.get() - 1)
            self.resetVal()
            del self.previousTransactionButtonList3[:]#delete/clear previous transaction
        else:
            print('no previous transaction found')

    def seatCounter(self,taken,show): #to count available seats
        if(show == 1):
            self.available_seats1.set(self.available_seats1.get() - taken)
        elif(show == 2):
            self.available_seats2.set(self.available_seats2.get() - taken)
        else:
            self.available_seats3.set(self.available_seats3.get() - taken)
    #just to initially update the variables
    def resetVal(self):
        ticketSold1 = 250 - self.available_seats1.get()
        ticketSold2 = 150 - self.available_seats2.get()
        ticketSold3 = 150 - self.available_seats3.get()
        self.totalTicketsSold.set(ticketSold1 + ticketSold2 + ticketSold3)
        self.totalIncome.set((ticketSold1 * 5) + (ticketSold2 * 5) + (ticketSold3 * 12))
#CLICK ON SEAT/BUTTON
    def SeatClick(self,seat_no):
        show = self.currentShow.get()
        action = 0
        if(show == '10Am Show'):
            action = self.button_list1[seat_no]['bg']
        elif(show == '3Pm Show'):
            action = self.button_list2[seat_no]['bg']
        elif(show == '8Pm Show'):
            action = self.button_list3[seat_no]['bg']
        else:
            return False
        if(action == '#f99999'):
            print('already bought')
        else:
            if(show == '10Am Show'):
                if(seat_no in self.selected_button_list1):#IF Seat/Button already selected, then remove    .after(1000, self.update_clock)
                    self.button_list1[seat_no].config(bg='SystemButtonFace')
                    self.selected_button_list1.remove(seat_no)
                    self.seats_being_bought1.set(str(len(self.selected_button_list1)))
                    self.totalPrice1.set(self.pricePerTicket1.get() * len(self.selected_button_list1))
                else:
                    self.button_list1[seat_no].config(bg='#00f0ff')#IF Seat/Button not selected then toggle it
                    self.selected_button_list1.append(seat_no)
                    self.seats_being_bought1.set(str(len(self.selected_button_list1)))
                    self.totalPrice1.set(self.pricePerTicket1.get() * len(self.selected_button_list1))
            elif(show == '3Pm Show'):
                if(seat_no in self.selected_button_list2):
                    self.button_list2[seat_no].config(bg='SystemButtonFace')#IF Seat/Button already selected, then remove
                    self.selected_button_list2.remove(seat_no)
                    self.seats_being_bought2.set(str(len(self.selected_button_list2)))
                    self.totalPrice2.set(self.pricePerTicket2.get() * len(self.selected_button_list2))
                else:
                    self.button_list2[seat_no].config(bg='#00f0ff')#IF Seat/Button not selected then toggle it
                    self.selected_button_list2.append(seat_no)
                    self.seats_being_bought2.set(len(self.selected_button_list2))
                    self.totalPrice2.set(self.pricePerTicket2.get() * len(self.selected_button_list2))
            else:
                if(seat_no in self.selected_button_list3):
                    self.button_list3[seat_no].config(bg='SystemButtonFace')#IF Seat/Button already selected, then remove
                    self.selected_button_list3.remove(seat_no)
                    self.seats_being_bought3.set(str(len(self.selected_button_list3)))
                    self.totalPrice3.set(self.pricePerTicket3.get() * len(self.selected_button_list3))
                else:
                    self.button_list3[seat_no].config(bg='#00f0ff')#IF Seat/Button not selected then toggle it 613553
                    self.selected_button_list3.append(seat_no)
                    self.seats_being_bought3.set(len(self.selected_button_list3))
                    self.totalPrice3.set(self.pricePerTicket3.get() * len(self.selected_button_list3))

# SHOW SELECTION
    def tenAmShow(self):
        UI_Class.tenAmShowBtn.config(bg='#00f0ff')
        self.threePmShowBtn.config(bg=self.white)
        self.eightPmShowBtn.config(bg=self.white)
        self.currentShow.set('10Am Show')
        self.seat_amountEntry.config(textvariable = self.available_seats1)
        self.seatsBeingBoughtVal.config(textvariable=self.seats_being_bought1)
        self.pricePerTicketVal.config(textvariable=self.pricePerTicket1)
        self.totalPriceVal.config(textvariable=self.totalPrice1)
        self.seat_amountTotal.config(textvariable=self.total_seats1)
        self.f1.grid()
        self.f2.grid_remove()
        self.f3.grid_remove()

    def threePmShow(self):
        self.threePmShowBtn.config(bg='#00f0ff')
        self.tenAmShowBtn.config(bg=self.white)
        self.eightPmShowBtn.config(bg=self.white)
        self.currentShow.set('3Pm Show')
        self.seat_amountEntry.config(textvariable = self.available_seats2)
        self.seatsBeingBoughtVal.config(textvariable=self.seats_being_bought2)
        self.pricePerTicketVal.config(textvariable=self.pricePerTicket2)
        self.totalPriceVal.config(textvariable=self.totalPrice2)
        self.seat_amountTotal.config(textvariable=self.total_seats2)
        self.f1.grid_remove()
        self.f2.grid()
        self.f3.grid_remove()

    def eightPmShow(self):
        self.eightPmShowBtn.config(bg='#00f0ff')
        self.tenAmShowBtn.config(bg=self.white)
        self.threePmShowBtn.config(bg=self.white)
        self.currentShow.set('8Pm Show')
        self.seat_amountEntry.config(textvariable = self.available_seats3)
        self.seatsBeingBoughtVal.config(textvariable= self.seats_being_bought3)
        self.pricePerTicketVal.config(textvariable=self.pricePerTicket3)
        self.totalPriceVal.config(textvariable=self.totalPrice3)
        self.seat_amountTotal.config(textvariable=self.total_seats3)
        self.f1.grid_remove()
        self.f2.grid_remove()
        self.f3.grid()

#BUTTON/SEAT CREATION AND DISPLAY
    def createSeats(self,num_of_seats,frame_pointer):
        col = num_of_seats / 10
        if(frame_pointer == 1):
            seat_counter1 = 1
            for x in range(int(col)):
                X = x + 10
                for y in range(1, 11):
                    taken_seats = randint(1,3)
                    if(taken_seats == 3):
                        b1 = Button(
                            self.f1, text='Seat%d' % seat_counter1,
                            name='seat%d' % seat_counter1, bg='#ff0000'
                        )
                        b1.grid(row=X, column=y)
                        seat_counter1 += 1
                        self.seatCounter(1, 1)
                    else:
                        b1 = Button(
                            self.f1, text='Seat%d' % seat_counter1,
                            name='seat%d' % seat_counter1,command= lambda j = seat_counter1: self.SeatClick(j)
                        )
                        b1.grid(row=X, column=y)
                        self.button_list1[seat_counter1] = b1
                        seat_counter1 += 1
        elif(frame_pointer == 2):
            seat_counter2 = 1
            for x in range(int(col)):
                X = x + 10
                for y in range(1, 11):
                    taken_seats = randint(1,3)
                    if(taken_seats == 3):
                        b2 = Button(
                            self.f2, text='Seat%d' % seat_counter2,
                            name='seat%d' % seat_counter2, bg='#ff0000'
                        )
                        b2.grid(row=X, column=y)
                        seat_counter2 += 1
                        self.seatCounter(1, 2)
                    else:
                        b2 = Button(
                            self.f2, text='Seat%d' % seat_counter2,
                            name='seat%d' % seat_counter2,command= lambda j = seat_counter2: self.SeatClick(j)
                        )
                        b2.grid(row=X, column=y)
                        self.button_list2[seat_counter2] = b2
                        seat_counter2 += 1
        else:
            seat_counter3 = 1
            for x in range(int(col)):
                X = x + 10
                for y in range(1, 11):
                    taken_seats = randint(1,3)
                    if(taken_seats == 3):
                        b3 = Button(
                            self.f3, text='Seat%d' % seat_counter3,
                            name='seat%d' % seat_counter3, bg='#ff0000'
                        )
                        b3.grid(row=X, column=y)
                        seat_counter3 += 1
                        self.seatCounter(1, 3)
                    else:
                        b3 = Button(
                            self.f3, text='Seat%d' % seat_counter3,
                            name='seat%d' % seat_counter3,command= lambda j = seat_counter3: self.SeatClick(j)
                        )
                        b3.grid(row=X, column=y)
                        self.button_list3[seat_counter3] = b3
                        seat_counter3 += 1

    def displaySeats(self,show):
        if(show == 10):
            self.available_seats1.set(250)
            self.createSeats(250, 1)
        elif(show == 3):
            self.available_seats2.set(150)
            self.createSeats(150, 2)
        else:
            self.available_seats3.set(150)
            self.createSeats(150, 3)
        self.resetVal()

if __name__ == '__main__':
    root = Tk()
    w, h = root.winfo_screenwidth(), root.winfo_screenheight()
    #root.overrideredirect(1) #removes menubar
    root.focus_set() # &lt;-- move focus to this widget
    root.geometry("%dx%d+0+0" % (w, h))
    root.title("Circus ticketing system")

    UI_Class = GUI(root)
    Program_Class = Program()

    root.mainloop()
</code></pre>

<p>the <code>Program_Class</code> object is instantiated after the <code>UI_Class</code> object and the latter doesn't reference the prior. Try passing <code>Program_Class</code> to the <code>GUI</code> constructor:</p>

<pre><code>Program_Class = Program()
UI_Class = GUI(root, Program_Class)
</code></pre>

<p>where:</p>

<pre><code>class GUI:
    def __init__(self, parent, program):
        self.program = program
</code></pre>

<p>then you should be able to reference <code>self.program</code>.</p>

python tkinter