how to remove a circular dependency in tkinter gui

Question

I'm in the very early stages of making a GUI. Right now I have the log in view(LogInWind class) and the sign up view (SignUpWind class). Everything was fine when I only had one view but now I have a circular dependency with these two objects. This happens with the buttons' command since in the log in view there is a button that takes you to the sign up view and vise versa. I think I could just make a pop up window for the sign up view. Yet I think the way I'm switching windows is a bad practice an may bring bigger issues later on.

I'm project structure is the following.

the services package will do the connection between the gui and the database. At the moment it does nothing.

I'm happy to get feedback for everything. If further explanation is needed I'm happy to do so.

root.py

import tkinter as tk
from .log_in_window import LogInWind as LIWind
from .sign_up_window import SignUpWind as SuWind
from services.messenger import Messenger


class Root(tk.Tk):
    def __init__(self, *args,**kwargs):
        super().__init__(*args,**kwargs)
        
        # General variables.
        self.frames = {}
        self.width_window
        self.height_window
        self.container = tk.Frame(self,relief="groove")

        # General app configurations.
        self.title("SECOM")
        self.iconbitmap("C:/Users/joshu/Documents/VSC/python/secom/icons/icon.ico")
        self.configure(bg="#E0E0E0")
        
        # Container setup.
        self.container.pack(side="top", fill="both", expand=True)
        self.container.grid_rowconfigure(0, weight=1)
        self.container.grid_columnconfigure(0, weight=1)


    def createFrame(self, page_name):
        """
        INPUT: view object. 
        OUTPUT: None

        Description: creates frame for the view `page_name`.
        """
        # Setup `newFrame.`
        newFrame = page_name(parent=self.container, controller=self)
        newFrame.configure(bg="#E0E0E0")
        newFrame.grid(row=0, column=0, sticky=tk.NSEW)

        # Add `newFrame` to catalog of frames.
        self.__frames[page_name] = newFrame
        

    def showFrame(self, page_name):
        """
        INPUT: view object.
        OUTPUT: None.

        Calls the view `page_name` up front for display.
        """

        try:
            # Bings requested view to the front.
            self.frames[page_name].tkraise()
        except KeyError:
            # Creates view and displays it.
            self.createFrame(page_name)
            self.frames[page_name].tkraise()


    def setLocation(self):
        """
        INPUT: None
        OUTPUT: None

        Description: Sets window in the middle of the screen.
        """
        self.widthWindow = 400
        self.heightWindow = 225
        widthScreen = self.winfo_screenwidth()
        hightScreen = self.winfo_screenheight()
        x = (widthScreen / 2) - (self.widthWindow / 2)
        y = (hightScreen / 2) - (self.heightWindow / 2)

        self.geometry("%dx%d+%d+%d" % (self.widthWindow, self.heightWindow, x, y))

log_in_window.py

import tkinter as tk
import tkinter.font as tkf
from .sign_up_window import SignUpWind as SUWind  # <-- circular dependency


class LogInWind(tk.Frame):
    def __init__(self, parent, controller):
        super().__init__(parent, controller)
        
        # Creation of labels.
        self.titleLbl = tk.Label(self,
                                 text="Iniciar Secion",
                                 font=tkf.Font(family="Helvetica", size=15, weight="bold"),
                                 bg="#E0E0E0")
        self.userLbl = tk.Label(self,
                                text="Usuario:",
                                font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                bg="#E0E0E0")
        self.pswdLbl = tk.Label(self,
                                text="Contraseña:",
                                font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                bg="#E0E0E0")
        # Creation of entries.
        self.userEty = tk.Entry(self)   
        self.pswdEty = tk.Entry(self, show="*")
        # Creation of buttons.
        self.logInBtn = tk.Button(self,
                                  width=15,
                                  text="Iniciar Sesion",
                                  font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                  bg="#0080FF",
                                  ################################### ADD COMMAND
                                  fg="#fff")
        self.signUpBtn  = tk.Button(self,
                                    width=15,
                                    text="Crear cuenta",
                                    font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                    bg="#0080FF",
                                    command=lambda: controller.showFrame(SUWind),  # <---- use object HERE.
                                    fg="#fff")

        # Places labels.
        self.titleLbl.grid(row=0,
                           column=0,
                           padx=400 / 2 - 60,
                           pady=10,sticky=tk.SW)
        self.userLbl.grid(row=1,
                          column=0,
                          padx=parent.width_window / 2 - 60,
                          sticky=tk.SW)
        self.pswdLbl.grid(row=3,
                          column=0,
                          padx=parent.width_window / 2 - 60,
                          sticky=tk.W)
        # Places entries (string inputs).
        self.userEty.grid(row=2,
                          column=0,
                          padx=parent.width_window / 2 - 60,
                          pady=5)
        self.pswdEty.grid(row=4,
                          column=0,
                          padx=parent.width_window / 2 - 60,
                          pady=5)
        # # Places buttons
        self.logInBtn.grid(row=5,column=0, sticky=tk.N)
        self.signUpBtn.grid(row=6, column=0, sticky=tk.S, pady=10)

sing_up_window.py

import tkinter as tk
import tkinter.font as tkf
from .log_in_window import LogInWind as LIWind # <-- circular dependency


class SignUpWind(tk.Frame):
    def __init__(self, parent, controller): 
        super().__init__(parent, controller)
        # Setup imge for back button.
        self.img = tk.PhotoImage(file="C:/Users/joshu/Documents/VSC/python/secom/icons/return.png")
        self.img = self.img.subsample(4,4)
        # Create label.
        self.titleLbl = tk.Label(self,
                                 text="Crear cuenta nueva",
                                 font=tkf.Font(family="Helvetica", size=15, weight="bold"),
                                 bg="#E0E0E0")
        self.userLbl = tk.Label(self,
                                text="Usuario:",
                                font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                bg="#E0E0E0")
        self.pswdLbl = tk.Label(self,
                                text="Contraseña:",
                                font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                bg="#E0E0E0")
        self.pswdConfirmLbl = tk.Label(self,
                                 text="Cormirma Contraseña:",
                                 font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                 bg="#E0E0E0")
        # Creation of entries.
        self.userEty = tk.Entry(self)
        self.pswdEty = tk.Entry(self, show="*")
        self.pswdConfirmEty = tk.Entry(self, show="*")                                 
        # Creation of button.
        self.backBtn = tk.Button(self,
                                 image=self.img,
                                 command=lambda: controller.showFrame(LIWind))   <----- use object HERE.
        self.CreateBtn = tk.Button(self,
                                   width=8,
                                   text="Crear",
                                   font=tkf.Font(family="Helvetica", size=10, weight="bold"),
                                   bg="#0080FF",
                                   ############################ ADD COMAND
                                   fg="#fff")


        # Places labels.
        self.titleLbl.grid(row=0, column=0, padx=400 / 2 - 90, sticky=tk.SW)
        self.userLbl.grid(row=1, column=0, padx=parent.width_window / 2 - 60, sticky=tk.W)
        self.pswdLbl.grid(row=3, column=0, padx=parent.width_window / 2 - 60, sticky=tk.W)
        self.pswdConfirmLbl.grid(row=5, column=0, padx=parent.width_window / 2 - 60, sticky=tk.W)
        # Places entries (string inputs).
        self.userEty.grid(row=2, column=0, padx=parent.width_window / 2 - 60, pady=5, sticky=tk.W)
        self.pswdEty.grid(row=4, column=0, padx=parent.width_window / 2 - 60, pady=5, sticky=tk.W)
        self.pswdConfirmEty.grid(row=6, column=0, padx=parent.width_window / 2 - 60, pady=5, sticky=tk.W)
        # Places buttons
        self.backBtn.grid(row=0, column=0,sticky=tk.W)
        self.CreateBtn.grid(row=7, column=0, padx=100,sticky=tk.N)

main.py

from views.root import Root
from views.log_in_window import LogInWind as LIWind


if __name__ == '__main__':
    root = Root()

    root.showFrame(LIWind)
    
    root.mainloop()

Answer 1

If you design your code so that you pass in the page name as a string rather than as a class then you won't have this problem.

For example, in root.py you can start with something like this:

pages = {
    "log in": LIWind,
    "sign up": SuWind,
}

Next, in createFrame you would do something like this:

def createFrame(self, page_name):
    ...
    cls = pages[page_name]
    newFrame = cls(parent=self.container, controller=self)
    ...
    self.__frames[page_name] = newFrame

Then, anywhere you need the window you can pass in the page name, such as:

self.backBtn = tk.Button(..., command=lambda: controller.showFrame("log in"))