How to correctly use 'in_' argument in tkinter grid()?

[Peter Otten]

jfong at ms4.hinet.net wrote:

> I had tried the following script test.py:
> --------
> import tkinter as tk
> 
> class Demo(tk.Frame):
>     def __init__(self):
>         tk.Frame.__init__(self, name='demo')
>         self.pack()
>         
>         panel = tk.Frame(self, name='panel')
>         panel.pack()
>         
>         start = tk.Button(text='Start', name='start')
>         start.grid(in_=panel)
>         
>         btn = self.nametowidget('panel.start')
>         btn.config(state='disabled')
> 
> Demo().mainloop()
> --------
> 
> It fails on nametowidget() function. My intention is to use 'in_' to
> change the parent of 'start' widget from the default Tk object to 'panel',
> but failed with KeyError: 'start'.
> 
> below is part of the snapshot in pdb,
> ...
>> d:\works\python\test.py(11)__init__()
> -> start = tk.Button(text='Start', name='start')
> (Pdb) !panel.winfo_parent()
> '.demo'
> (Pdb) next
>> d:\works\python\test.py(12)__init__()
> -> start.grid(in_=panel)
> (Pdb) !start.winfo_parent()
> '.'
> (Pdb) next
>> d:\works\python\test.py(14)__init__()
> -> btn = self.nametowidget('panel.start')
> (Pdb) !start.winfo_parent()
> '.'
> 
> --Jach

I think that the `in_` argument is used correctly. It's just that your 
expectation that the name is changed to reflect the layout hierarchy is 
wrong. 

To manipulate the start button you can use the `start` variable directly:

start.config(state='disabled')

To find all slaves of the panel use

panel.grid_slaves()

$ cat grid_in.py
import tkinter as tk

class Demo(tk.Frame):
    def __init__(self):
        tk.Frame.__init__(self, name='demo')
        self.pack()
        
        self.panel = panel = tk.Frame(self, name='panel')
        panel.pack()
        
        start = tk.Button(text='Start', name='start')
        start.grid(in_=panel)
        
        for btn in panel.grid_slaves():
            print("disabling", btn._w)
            btn.config(state='disabled')

Demo() #.mainloop()
$ python3 grid_in.py 
disabling .start
$