Can't destroy inherited tkinter.Tk() window - python-3.x

Question

I'm having a ton of trouble killing a tkinter window created using the below fashion. I'm getting the error shown below. I'm pretty new to Python, so any help would be greatly appreciated.
class InspectWindow(tk.Frame):
def __init__(self, sender_email, recipient_email, email_body,
master = None):
super().__init__(master)
self.create_widgets()
def create_widgets(self):
self.yes = tk.Button(self)
self.yes['text'] = 'send me!'
self.yes['command'] = self.send_email()
def send_email(self):
root.destroy()
root = tk.Tk()
popup = InspectWindow(sender_email, recipient_email, email_body,
master=root)
popup.mainloop()
Traceback (most recent call last):
File "spam.py", line 108, in <module>
master=root)
File "spam.py", line 16, in __init__
self.create_widgets()
File "AutomateFellowshipEmails.py", line 23, in create_widgets
self.yes['command'] = self.send_email()
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/tkinter/__init__.py", line 1486, in __setitem__
self.configure({key: value})
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/tkinter/__init__.py", line 1479, in configure
return self._configure('configure', cnf, kw)
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/tkinter/__init__.py", line 1470, in _configure
self.tk.call(_flatten((self._w, cmd)) + self._options(cnf))
_tkinter.TclError: invalid command name ".!inspectwindow.!button"

Answer 1

The problem is this line of code:
self.yes['command'] = self.send_email()
It is the exact same as if you did this:
result = self.send_email()
self.yes['command'] = reuslt
Since self.send_email() destroys the root window and then returns None, it's the same as doing this:
root.destroy()
self.yes['command'] = None
Once you destroy the root widget -- which causes all other widgets to be destroyed -- you will get an error anytime you try to call a method on a widget. When you try to configure self.yes, self.yes no longer exists so you get an error.
The solution is to pass a reference to the function of a button so that you don't immediately call it. You do it like this:
self.yes['command'] = self.send_email
Notice the lack of parenthesis on self.send_email. Instead of calling the function immediately, you are telling tk "here is the name of a function that I want you to call when the user clicks the button".

Answer 2

you must keep a reference of master in order to call methods on it.
(and a few other errors too)
something like this (I removed undefined variables mail, etc...)
import tkinter as tk
class InspectWindow(tk.Frame): # if this is a popup, you may like to inherit from tk.TopLevel?
def __init__(self, master = None): # removed undefined variables, you can put them back in
self.master = master # keep a reference of master
super().__init__(self.master)
self.create_widgets()
self.pack() # pack into parent window
def create_widgets(self):
self.yes = tk.Button(self)
self.yes['text'] = 'send me!'
self.yes['command'] = self.send_email # removed () call, this takes a method, not a method call
self.yes.pack() # pack into self
def send_email(self):
self.master.destroy() # call destroy on self.master
# maybe you want to call on self instead, depending what you want to destroy
root = tk.Tk()
popup = InspectWindow(master=root) # removed undefined variables, you can put them back in
popup.mainloop()