I started programming in Python on Monday. I have enjoyed learning it. But I am stuck trying to understand how to avoid recursion when switching between tkinter menus! I am sure this is a very basic question, and I appreciate you tolerating my ignorance on this subject, but I have been unable to find an answer elsewhere.
What I am now doing is, eventually, giving me the error: RuntimeError: maximum recursion depth exceeded while calling a Python object
This is the pattern I am currently using. UPDATED: The code below is now a full, isolated copy reproducing the problem I am facing! :D
from tkinter import *
def mainmenu():
global frame, root
frame.destroy()
frame = Frame()
frame.pack()
button1 = Button(frame, text="anothermenulikethis", command = anothermenulikethis)
button2 = Button(frame, text="anothermenulikethis", command = anothermenulikethis)
button3 = Button(frame, text="mainmenu", command = mainmenu)
button1.pack(side=LEFT)
button2.pack(side=LEFT)
button3.pack(side=LEFT)
root.mainloop()
def anothermenulikethis():
global frame, root
frame.destroy()
frame = Frame()
frame.pack()
button1 = Button(frame, text="mainmenu", command = mainmenu)
button2 = Button(frame, text="mainmenu", command = mainmenu)
button3 = Button(frame, text="anothermenulikethis", command = anothermenulikethis)
button1.pack(side=LEFT)
button2.pack(side=LEFT)
button3.pack(side=LEFT)
root.mainloop()
root = Tk()
root.title("Recursive Menu Problem Isolation")
root.geometry("1200x600")
frame = Frame()
mainmenu()
And it all works fine, until its inevitable failure from maximum recursion depth. If anyone can suggest a better way of doing things, or has a link to an example of a better way of doing this, I am eager to learn.
PS: I have looked at and tried increasing the recursion depth, but I feel that is a poor man's solution to what is a fundamental problem with my approach.
Thank you in advance, everyone.
As requested, here is the traceback:
Exception in Tkinter callback
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/tkinter/__init__.py", line 1399, in __call__
return self.func(*args)
File "/Users/diligentstudent/Desktop/menutest.py", line 11, in mainmenu
button1 = Button(frame, text="anothermenulikethis", command = anothermenulikethis)
File "/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/tkinter/__init__.py", line 2028, in __init__
Widget.__init__(self, master, 'button', cnf, kw)
File "/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/tkinter/__init__.py", line 1958, in __init__
(widgetName, self._w) + extra + self._options(cnf))
File "/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/tkinter/__init__.py", line 1043, in _options
v = self._register(v)
File "/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/tkinter/__init__.py", line 1079, in _register
f = CallWrapper(func, subst, self).__call__
RuntimeError: maximum recursion depth exceeded
Only one mainloop()
is needed to handle a tkinter GUI.
With that said, I think you just need an example of the class structure:
from tkinter import Tk,Button
class Application(Tk):
def say_hi(self):
print('Hello world?!')
def close_app(self):
self.destroy()
def create_Widgets(self):
self.quitButton = Button(self, width=12, text='Quit', bg='tan',
command=self.close_app)
self.quitButton.grid(row=0, column=0, padx=8, pady=8)
self.helloButton = Button(self, width=12, text='Hello',
command=self.say_hi)
self.helloButton.grid(row=0, column=1, padx=8, pady=8)
def __init__(self):
Tk.__init__(self)
self.title('Hello world!')
self.create_Widgets()
app = Application()
app.mainloop()
To avoid possible conflicts with other modules, some people prefer importing like this
(clearly stating where everything comes from):
import tkinter as tk
class Application(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
self.title('Hello world!')
self.quitButton = tk.Button(self, width=12, text='Quit', bg='tan',
command=self.close_app)
self.quitButton.grid(row=0, column=0, padx=8, pady=8)
self.helloButton = tk.Button(self, width=12, text='Hello',
command=self.say_hi)
self.helloButton.grid(row=0, column=1, padx=8, pady=8)
def say_hi(self):
print('Hello world?!')
def close_app(self):
self.destroy()
app = Application()
app.mainloop()
And as you can see, creating the widgets can easily happen in the __init__
I decided to make a more practical / educational example based on what I've learned in the past month. While doing so I had a bit of a revelation: not everything requires a self. prefix in a class! This is especially true with a tkinter class, because you aren't manipulating it as an object in the main program. Mostly you need the self. prefix when you are going to use something in a method later. The previous examples display how anything (like the buttons) can receive a self. prefix, even when completely unnecessary.
Some things this example will show:
• pack()
and grid()
can be used in the same GUI as long as they don't share a master.
• A Text widget can be made to not expand when the font size changes.
• How to toggle a bold tag on and off of selected text.
• How to truly center a GUI on the screen. (more information here)
• How to make a Toplevel window appear in the same location relative to the main window.
• Two ways to prevent a Toplevel window from being destroyed, so it only needs to be created once.
• Make ctrl+a (select all) function properly.
import tkinter as tk
import tkFont
class Application(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
self.title('T-Pad')
# Menubar
menubar = tk.Menu(self)
filemenu = tk.Menu(menubar, tearoff=0)
filemenu.add_command(label="Exit", command=self.close_app)
menubar.add_cascade(label="File", menu=filemenu)
formatmenu = tk.Menu(menubar, tearoff=0)
formatmenu.add_command(label="Font", command=self.show_sizeWin)
menubar.add_cascade(label="Format", menu=formatmenu)
self.config(menu=menubar)
# Bold Button
boldButton = tk.Button(self, width=12, text='Bold',
command=self.make_bold)
boldButton.pack()
# Text widget, its font and frame
self.defaultFont = tkFont.Font(name="defFont")
textFrame = tk.Frame(self, borderwidth=1, relief="sunken",
width=600, height=600)
textFrame.grid_propagate(False) # ensures a consistent GUI size
textFrame.pack(side="bottom", fill="both", expand=True)
self.mText = tk.Text(textFrame, width=48, height=24, wrap='word',
font="defFont")
self.mText.grid(row=0, column=0, sticky="nsew")
# Scrollbar and config
tScrollbar = tk.Scrollbar(textFrame, command=self.mText.yview)
tScrollbar.grid(row=0, column=1, sticky='nsew', pady=1)
self.mText.config(yscrollcommand=tScrollbar.set)
# Stretchable
textFrame.grid_rowconfigure(0, weight=1)
textFrame.grid_columnconfigure(0, weight=1)
# Bold Tag
self.bold_font = tkFont.Font(self.mText, self.mText.cget("font"))
self.bold_font.configure(weight="bold")
self.mText.tag_configure("bt", font=self.bold_font)
# Center main window
self.update_idletasks()
xp = (self.winfo_screenwidth() / 2) - (self.winfo_width() / 2) - 8
yp = (self.winfo_screenheight() / 2) - (self.winfo_height() / 2) - 30
self.geometry('{0}x{1}+{2}+{3}'.format(self.winfo_width(), self.winfo_height(),
xp, yp))
# Font Size Window (notice that self.sizeWin is given an alias)
sizeWin = self.sizeWin = tk.Toplevel(self, bd=4, relief='ridge')
self.sizeList = tk.Listbox(sizeWin, width=10, height=17, bd=4,
font=("Times", "16"), relief='sunken')
self.sizeList.grid()
doneButton = tk.Button(sizeWin, text='Done', command=sizeWin.withdraw)
doneButton.grid()
for num in range(8,25):
self.sizeList.insert('end', num)
sizeWin.withdraw()
sizeWin.overrideredirect(True) # No outerframe!
# Below is another way to prevent a TopLevel window from being destroyed.
# sizeWin.protocol("WM_DELETE_WINDOW", self.callback)
# Bindings
# Double click a font size in the Listbox
self.sizeList.bind("<Double-Button-1>", self.choose_size)
self.bind_class("Text", "<Control-a>", self.select_all)
## def callback(self):
## self.sizeWin.withdraw()
def select_all(self, event):
self.mText.tag_add("sel","1.0","end-1c")
def choose_size(self, event=None):
size_retrieved = self.sizeList.get('active')
self.defaultFont.configure(size=size_retrieved)
self.bold_font.configure(size=size_retrieved)
def show_sizeWin(self):
self.sizeWin.deiconify()
xpos = self.winfo_rootx() - self.sizeWin.winfo_width() - 8
ypos = self.winfo_rooty()
self.sizeWin.geometry('{0}x{1}+{2}+{3}'.format(self.sizeWin.winfo_width(),
self.sizeWin.winfo_height(), xpos, ypos))
def make_bold(self):
try:
current_tags = self.mText.tag_names("sel.first")
if "bt" in current_tags:
self.mText.tag_remove("bt", "sel.first", "sel.last")
else:
self.mText.tag_add("bt", "sel.first", "sel.last")
except tk.TclError:
pass
def close_app(self):
self.destroy()
app = Application()
app.mainloop()
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