Why is program giving NameError even after defining function? [duplicate]

Question

I want to bind a function to open a new window with form to fill details with a 'Register' button. But even after defining the register() function, it gives NameError when I click the button.

Tried with: 1) 'command=function" method 2) btn.bind() method Still giving error.

register_btn = Button(main_screen,text = "Register", bg = "grey",width = "30", height = "2")
register_btn.pack()
register_btn.bind("<Button-1>", register)

#function
def register(event):
---

Exception has occurred: NameError name 'register' is not defined

Answer 1

You need to define the function before you actually call it, unless you're using classes of course.

#function
def register(event):
    pass

register_btn = Button(main_screen,text = "Register", bg = "grey",width = "30", height = "2")
register_btn.pack()
register_btn.bind("<Button-1>", register)