Python3.6 tkinter bug?

[Peter Smith]

On Wednesday, February 1, 2017 at 11:55:35 AM UTC, Terry Reedy wrote:
> On 2/1/2017 1:37 AM, Christian Gollwitzer wrote: 
> > Am 01.02.17 um 00:02 schrieb MRAB: 
> >> On 2017-01-31 22:34, Christian Gollwitzer wrote: 
> >>>> .!frame.!checkbutton 
> >>>> .!frame.!checkbutton2 
> >>>> .!frame2.!checkbutton 
> >>>> .!frame2.!checkbutton2 
> >>> 
> >>> 
> >> Perhaps someone who knows Tcl and tk can tell me, but I notice that in 
> >> the first example, the second part of the widget names are unique, 
> >> whereas in the second example, the second part of the widget names are 
> >> the reused (both "!checkbutton" and "!checkbutton2" occur twice). 
> > 
> > It is indeed the reason, but it has some strange legacy cause: the 
> > default name for the checkbutton-linked variable is the name of the 
> > button inside the parent. Therefore creating a checkbutton has the side 
> > effect of creating a variable with the button's name. 
> > 
> > In this case, the first buttons in the frames are linked to a variable 
> > called "!checkbutton" and the other two are linked to "!checkbutton2". 
> > (a variable name in Tcl can be anything apart from the empty string). 
> > This can also be demonstrated by this Tcl script: 
> > 
> > package require Tk 
> > 
> > pack [frame .f1] 
> > pack [frame .f2] 
> > 
> > pack [checkbutton .f1.c1 -text "A" ] 
> > pack [checkbutton .f1.c2 -text "B" ] 
> > 
> > pack [checkbutton .f2.c1 -text "C" ] 
> > pack [checkbutton .f2.c2 -text "D" ] 
> > 
> > which is equivalent to the Python code above. 
> > 
> > Note that this surprising behaviour was corrected for the (modern) ttk 
> > widgets, so if "checkbutton" is replaced by "ttk::checkbutton", they are 
> > not any longer linked. In Python, that would be 
> > 
> > from tkinter import ttk 
> > ... 
> > w = ttk.Checkbutton() 
> > 
> > (Personally, I'm not using the legacy widgets any longer)
> Christian, could you repeat any relevant parts of your comments on the 
> tracker, especially any ideas on how we might fix tkinter? 
> https://bugs.python.org/issue29402
> >> Do the names need to be: 
> >> 
> >> .!frame.!checkbutton 
> >> .!frame.!checkbutton2 
> >> .!frame2.!checkbutton3 
> >> .!frame2.!checkbutton4
> Serhiy considered that but, not knowing that this would cause a 
> regression, we both liked numbering within parent better. 
> 
> There is a similar issue with radiobuttons on ttk.OptionMenus that 
> existed *before* the 3.6 name changes. 
> https://bugs.python.org/issue25684 
> So there seems to be a systematic issue with tk or how we are (mis)using it.
> > Good question. Maybe there should be unique variable names? I.e., if the 
> > script is changed into package require Tk 
> > 
> > pack [frame .f1] 
> > pack [frame .f2] 
> > 
> > pack [checkbutton .f1.c1 -text "A" -variable v1] 
> > pack [checkbutton .f1.c2 -text "B" -variable v2] 
> > 
> > pack [checkbutton .f2.c1 -text "C" -variable v3] 
> > pack [checkbutton .f2.c2 -text "D" -variable v4] 
> > 
> > then they are also not linked.
> -- 
> Terry Jan Reedy

It looks as if the issue is indeed that the expression to the right of CheckButton(... variable= must be an expression.

This works for me
   global checkbix, checkbuttons
   checkbix += 1
   b = tk.Checkbutton(frame, text=text, variable=checkbuttons[checkbix], ...)