Hello,
I would like to suggest that nonlocal should be given the same creating
power as global.
If I do
global a_var
it creates the global a_var if it doesn't exist.
I think it would be great that nonlocal maintained that power.
This way when I do
nonlocal a_var
it would create a_var in the imediate parent environment, if it didn't
exist.
Without nonlocal creation powers I have to create global variables or
local variables after master=Tk() (in the following example):
from tkinter import StringVar, Tk
from tkinter.ttk import Label
def start_gui():
def change_label():
_label_sv.set('Bye Bye')
def create_vars():
global _label_sv
_label_sv = StringVar(value='Hello World')
def create_layout():
Label(master, textvariable=_label_sv).grid()
def create_bindings():
master.bind('<Escape>', lambda _: master.destroy())
master.bind('<Return>', lambda _: change_label())
master = Tk()
create_vars()
create_layout()
create_bindings()
master.mainloop()
if __name__ == '__main__':
start_gui()
With nonlocal creation powers it would become a start_gui local variable
(no global) but I could have a function to create the vars instead of
having to add them after master=Tk():
from tkinter import StringVar, Tk
from tkinter.ttk import Label
def start_gui():
def change_label():
label_sv.set('Bye Bye')
def create_vars():
nonlocal label_sv
label_sv = StringVar(value='Hello World')
def create_layout():
Label(master, textvariable=label_sv).grid()
def create_bindings():
master.bind('<Escape>', lambda _: master.destroy())
master.bind('<Return>', lambda _: change_label())
master = Tk()
create_vars()
create_layout()
create_bindings()
master.mainloop()
if __name__ == '__main__':
start_gui()
I know that I could also do it with OOP, but this way is more concise
(OOP would add more lines and increase the lines length, which I
personally dislike)
This example is very simple, but if you imagine a GUI with several
widgets, then the separation between vars, layout and bindings becomes
useful for code organization.
Best regards,
João Matos
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