函数内的全局变量

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

Answer 1

在启动任何功能之前，请初始化lb。

Answer 2

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!