Python3 class function definition confusion about NameError - python-3.x

Question

I'm new to programming and this is my first post on the site. I'm sure I'm making a dumb mistake, but I'd really appreciate a push in the right direction. I'm trying to make a calculator, and want to make a function that produces a Button object for numbers. When I try to run this I get the error:
'NameError: name 'num_but_gen' is not defined'
Here is the code:
from tkinter import *
WINDOW_HEIGHT = 300
WINDOW_WIDTH = 325
class Window(Frame):
def __init__(self, master = None):
Frame.__init__(self, master)
self.master = master
self.init_window()
def num_but_gen(self, disp, xloc=0, yloc=0, wid=0, hei=0):
self.Button(text='{}'.format(disp),height=hei, width=wid)
self.place(x=xloc, y=yloc)
def init_window(self):
self.master.title('Calculator')
self.pack(fill=BOTH, expand=1)
Button1 = num_but_gen('1', xloc=0, yloc=200, wid=40, hei=40)
root = Tk()
app = Window(root)
root.geometry("{}x{}".format(WINDOW_WIDTH,WINDOW_HEIGHT))
root.mainloop()
Any help would be greatly appreciated! Also bonus points to anyone with suggestions on how to better phrase my question titles in future posts.

Answer 1

jasonharper is right, you need to add self in front of num_but_gen, but there are other problems in your code.
In num_but_gen:
your window class does not have a Button attribute, so you need to remove self. in front of Button
it is not the Window instance but the button that you want to place
you don't need to use text='{}'.format(disp), text=disp does the same.
In init_window:
you store the result of num_but_gen in a variable, but this function returns nothing so that's useless (and capitalized names should not be used for variables, but for class names only)
the width option of a button displaying text is in letters, not in pixels and its height option is in text lines, so wid=40, hei=40 will create a very big button. If you want to set the button size in pixels, you can do it through the place method instead.
Here is the corresponding code:
import tkinter as tk
WINDOW_HEIGHT = 300
WINDOW_WIDTH = 325
class Window(tk.Frame):
def __init__(self, master = None):
tk.Frame.__init__(self, master)
self.master = master
self.init_window()
def num_but_gen(self, disp, xloc=0, yloc=0, wid=0, hei=0):
button = tk.Button(self, text=disp)
button.place(x=xloc, y=yloc, height=hei, width=wid)
def init_window(self):
self.master.title('Calculator')
self.pack(fill=tk.BOTH, expand=1)
self.num_but_gen('1', xloc=0, yloc=200, wid=40, hei=40)
root = tk.Tk()
app = Window(root)
root.geometry("{}x{}".format(WINDOW_WIDTH,WINDOW_HEIGHT))
root.mainloop()