global variable within a function

Question

i am trying to tell one function to remove the button lb from the screen using place.forget() but i am getting an error because i have defined the button lb as a global variable within another function and so each time it tries to recall it it doesn't 'see' the global variable. I know why it's giving me the error i'm just unsure of how to correct it, any help would be greatly appreciated.

def page4():
    master.title('Page 4')
    #draw
    c19.grid(pady=slpady)
    c19.grid(row=sly,column=slx1)
    c20.grid(row=sly,column=slx2)
    c21.grid(row=sly,column=slx3)
    c22.grid(row=sly,column=slx4)
    c23.grid(row=sly,column=slx5)
    c24.grid(row=sly,column=slx6)
    rec.grid(row=rec_y, column=rec_x,columnspan=3)
    clear_4.grid(row=clear_y, column=clear_x,columnspan=3)
    #hide
    c1.grid_remove()
    c2.grid_remove()
    c3.grid_remove()
    c4.grid_remove()
    c5.grid_remove()
    c6.grid_remove()
    c7.grid_remove()
    c8.grid_remove()
    c9.grid_remove()
    c10.grid_remove()
    c11.grid_remove()
    c12.grid_remove()
    c13.grid_remove()
    c14.grid_remove()
    c15.grid_remove()
    c16.grid_remove()
    c17.grid_remove()
    c18.grid_remove()
    new_show.grid_remove()
    save_show.grid_remove()
    load_show.grid_remove()
    pre_1.grid_remove()
    pre_2.grid_remove()
    pre_3.grid_remove()
    pre_4.grid_remove()
    clear_1.grid_remove()
    clear_2.grid_remove()
    clear_3.grid_remove()
    lb.place_forget()

#Presets
def presets():
    master.title('Presets')
    pre_1.grid(row=1,column=1,padx=ppadx, pady=ppady)
    pre_2.grid(row=1,column=2,padx=ppadx, pady=ppady)
    pre_3.grid(row=2,column=1,padx=ppadx, pady=ppady)
    pre_4.grid(row=2,column=2,padx=ppadx, pady=ppady)
    global lb
    lb=Button(master,width=20,height=5,text='LOCK',bg='burlywood1',command=lockscreen)
    lb.place(x=450,y=580)

the error im getting is:

Exception in Tkinter callback Traceback (most recent call last):
    File "C:\Python27\lib\lib-tk\Tkinter.py", line 1470, in __call__
        return self.func(*args)
    File "C:\Users\Josh Bailey\Desktop\pi_dmx\pi_dmx512py2.py", line 412, in page4
        lb.place_forget() NameError: global name 'lb' is not defined

Possible duplicate of http://stackoverflow.com/questions/423379/using-global-variables-in-a-function-other-than-the-one-that-created-them — ddelemeny, Mar 09 '14 at 17:57

score 2 · Accepted Answer · answered Mar 09 '14 at 17:46

2

Initialize lb before you start any of the functions.

answered Mar 09 '14 at 17:46

La-comadreja

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@user2996828 what exact syntax did you try? – La-comadreja Mar 09 '14 at 18:37
i moved 'global lb' above everything so it was the first line and it still didn't work, why would i make it up? – user2996828 Mar 09 '14 at 20:00
1

move lb=Button(master... there too. – La-comadreja Mar 10 '14 at 01:25
1

Or even just put "lb=None" outside of all the functions, then make sure it is initialized in the `presets` function first. I think that would work. – djhoese Mar 10 '14 at 01:32

score 0 · Answer 2 · answered Mar 10 '14 at 09:46

I have solved it by moving the global lb and the lb=Button(master,width=20,height=5,text='LOCK',bg='burlywood1',command=lockscreen) to the top of my code so that it was out of any function and then had to rearrange the rest of my code so that the function being called by that button ( lockscreen) sat above the preset function. Thanks for the help!

global variable within a function

2 Answers2