Creating Windows in a 'For Loop' (Python)

Question

I've been creating a game using Python, and in one of my functions,

def Enemy_Party(enemies, party):
        def Sub_Fight(member, enemy, enemies, Prep):
            Prep.destroy()
            Fight(member, enemy, enemies)
        for x in enemies:
            Prep = Tk()
            for y in party:
                button = Button(Prep, text=y.name, command=Sub_Fight(y, x, enemies, Prep)).pack()
            Prep.mainloop()

a single window is created, but with nothing in it. There is no error message, the blank window just sits there.

Yes, I have a function Fight, and it does take four arguments. Both 'enemies' and 'party' are defined as lists, and both have values within them (I've checked).

On that note, I have two questions: "Why does the program halt after creating one blank window?" and "Can you define windows in a 'For Loop'?

Let me know if you need any more code, and thanks ahead of time.

Your snippet does not help much to demonstrate what is happening. Can you provide minimal working example demonstrating the issue you have? — Marcin
– Marcin, Commented Feb 3, 2015 at 1:07
Also, this button = Button(Prep, text=y.name, command=Sub_Fight(y, x, enemies, Prep)).pack() will result in button being null. The reason is that pack returns null. Maybe this is part of the issue you are having? — Marcin
– Marcin, Commented Feb 3, 2015 at 1:10

Bryan Oakley · Accepted Answer · 2015-02-03 02:48:33Z

3

The program halts the first time mainloop is called, because that's what mainloop does -- it doesn't return until you destroy the window.

You have a fundamental misunderstanding of how to create windows. Every tkinter application needs a single instance of Tk. To create additional windows you need to create instances of Toplevel. You then need to call mainloop exactly once.

In your code, replace calls to Tk with calls to Toplevel, then remove the call to mainloop in your function. Presumably you're calling mainloop somewhere else in your code after all of the widgets have been created.

answered Feb 3, 2015 at 2:48

Bryan Oakley

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Comments

James.D.Wood · Accepted Answer · 2015-02-03 01:11:39Z

0

I notice that you're defining Tk() inside a for loop. Depending on how many times this loop iterates, you could be creating many instances of Tk() when actually you should never create more than one. I would advise creating your window outside of the loop and populating it as you need to using the loop (or whatever else you may decide to use).

answered Feb 3, 2015 at 1:11

James.D.Wood

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4 Comments

David Noble Over a year ago

I was actually trying to create multiple windows, one for each 'y in party'. Is that possible? If not, can I create a Frame for each 'y'?

James.D.Wood Over a year ago

Yeah, you can have multiple windows, but only ONE "master" window (Tk()). Any additional windows need to be defined using Toplevel() instead. I.E., Prep = Toplevel(). You may need to check this, but I'm also pretty sure each window needs a unique name, so they can't ALL be "Prep".

David Noble Over a year ago

Thanks, that worked perfectly! . P.S. The program managed to create two windows named Prep using the loop.

James.D.Wood Over a year ago

Ok, nice one. I wasn't sure about the naming thing so good to hear that works fine.

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