Is it necessary to call Tk() when writing a GUI app with Tkinter?

[Rick Johnson]

On Feb 29, 11:24 pm, Terry Reedy <tjre... at udel.edu> wrote:
> On 2/29/2012 10:22 PM, Rick Johnson wrote:

> > PS: I would highly suggest against using the "from Tkinter import *".
> > Instead, use "import Tkinter as tk" and prefix all module contents
> > with "tk.".
>
> I have changed the example to do that. I also showed the alternate to
> initialize a widget. Here is the current version, tested on Windows 3.2.2.
>
> import tkinter as tk
>
> class Application(tk.Frame):
>      def __init__(self, master=None):
>          tk.Frame.__init__(self, master)
>          self.pack()

With all due respect, I would also recommend against "self packing" a
widget. And i can speak from experience on this issue. There was a
time when i was self-packing lots of custom compund widgets; then i
realized later the shortcomings of such action; what if you need to
use the grid or place geometry mangers instead? So remove the
self.pack line and add a line to the bottom:

> root = tk.Tk()
> app = Application(master=root)
> app.pack() # <-- added this line
> app.mainloop()


> There is a minor problem left. The hi_there Button text has underscores
> because if I use spaces instead, tk surrounds the text with {bra ces}.
> This seems bizarre. Is there any way to have Button text with spaces and
> no braces?

Not sure what is happening on your end, but i don't see any braces. In
any event, here is a slightly modified version of your code that
follows PEP8 and removes some inconsistencies.

## START CODE ##
# Python < 3.0
import Tkinter as tk
from Tkconstants import TOP, BOTTOM
from tkMessageBox import showinfo

class Application(tk.Frame):
     def __init__(self, master=None):
         tk.Frame.__init__(self, master)
         self.createWidgets()

     def createWidgets(self):
         self.hi_there = tk.Button(self)
         self.hi_there["text"] = "Hello_World\n(click_me)"
         self.hi_there["command"] = self.say_hi
         self.hi_there.pack() # !!!
         self.qbutton = tk.Button(self, text="Close Application",
                                  fg="red", command=root.destroy)
         self.qbutton.pack() # !!!

     def say_hi(self):
         showinfo('Modal Dialog', "hi there, everyone!", parent=self)
         print("hi there, everyone!")

if __name__ == '__main__':
    root = tk.Tk()
    app = Application(master=root)
    app.pack()
    app.mainloop()
## END CODE ##