'Gui' object has no attribute 'after'

Question

I took my working tkinter code (which only drew window/buttons and so on) and tried to add some code from the approved answer here: python code for serial data to print on window.

The approved answer works by itself with very small modifications, but added to my code I get the error "'Gui' object has no attribute 'after'"

What I don't understand is why the attribute "after" is looked for in class Gui instead of in method process_serial.

from tkinter import *
from tkinter import ttk

import serial
import threading
import queue

class SerialThread(threading.Thread):
    def __init__(self, queue):
        threading.Thread.__init__(self)
        self.queue = queue
    def run(self):
        s = serial.Serial('COM11',115200)
        while True:
            if s.inWaiting():
                text = s.readline(s.inWaiting())
                self.queue.put(text)

class Gui():
    def __init__(self, master):
        ###MAIN FRAME###
        mainFrame = Frame(master, width=50000, height=40000)
        mainFrame.pack(fill = BOTH, expand = 1)

        ###LIST FRAME###
        listFrame = Frame(mainFrame)
        listFrame.pack(side = TOP, fill = BOTH, expand = 1)

        self.sensorList = ttk.Treeview(listFrame)

        self.sensorList["columns"]=("MAC","Type","Value","Voltage","Firmware","Rate","RSSI")
        self.sensorList.column("MAC", width=200, minwidth=200)
        self.sensorList.column("Type", width=100, minwidth=100)
        self.sensorList.column("Value", width=100, minwidth=100)
        self.sensorList.column("Voltage", width=100, minwidth=100)
        self.sensorList.column("Firmware", width=100, minwidth=100)
        self.sensorList.column("Rate", width=100, minwidth=100)
        self.sensorList.column("RSSI", width=100, minwidth=100)
        self.sensorList.heading("MAC", text="MAC")
        self.sensorList.heading("Type", text="Type")
        self.sensorList.heading("Value", text="Value")
        self.sensorList.heading("Voltage", text="Voltage")
        self.sensorList.heading("Firmware", text="Firmware")
        self.sensorList.heading("Rate", text="Rate")
        self.sensorList.heading("RSSI", text="RSSI")

        self.sensorList.pack(fill = BOTH, expand = 1,  pady=5, padx=5)

        ###TEXT AREA FRAME###
        textAreaFrame = Frame(mainFrame)
        textAreaFrame.pack(side = TOP, fill = BOTH, expand = 1)

        self.textArea = Text(textAreaFrame)
        self.textArea.pack(fill = BOTH, expand = 1,  pady=5, padx=5)

        ###INPUT FRAME###
        inputFrame = Frame(mainFrame)
        inputFrame.pack(side = BOTTOM, fill = X, expand = 0)

        self.input = Entry(inputFrame)
        self.input.pack(side=LEFT, fill = X, expand = 1,  pady=5, padx=5)

        self.comboAction = ttk.Combobox(inputFrame)
        self.comboAction.pack(side = LEFT, pady=5, padx=5)

        self.comboDevice = ttk.Combobox(inputFrame)
        self.comboDevice.pack(side = LEFT, pady=5, padx=5)

        self.sendButton = Button(
            inputFrame, text="SEND", command=mainFrame.quit
        )

        self.sendButton.pack(side=LEFT,pady=5, padx=5)

        #self.button = Button(
        #   mainFrame, text="QUIT", fg="red", command=mainFrame.quit
        #)
        #self.button.pack(side=LEFT)

        #self.hi_there = Button(mainFrame, text="Hello", command=self.say_hi)
        #self.hi_there.pack(side=LEFT)

        ###AFFIX MINIMUM SIZE OF MAIN WINDOW TO PREVENT POOR SIZING###
        master.update()
        master.minsize(root.winfo_width(), root.winfo_height())
        master.minsize(master.winfo_width(), master.winfo_height())

        ###SERIAL PORT###
        self.queue = queue.Queue()
        thread = SerialThread(self.queue)
        thread.start()
        self.process_serial()

    def process_serial(self):
        while self.queue.qsize():
            try:
                self.textArea.delete(1.0, 'end')
                self.textArea.insert('end', self.queue.get())
            except Queue.Empty:
                pass
        self.after(100, self.process_serial)



    def say_hi(self):
        s = self.input.get()
        print ("hi there, everyone!" + s)

root = Tk()

gui = Gui(root)

root.mainloop()
root.destroy() # optional; see description below

Answer 1

The culprit is in this line in the process_serial function:

self.after(100, self.process_serial)

The self variable that is in here refers to the Gui object, not to a tkinter object that has the 'after' function.

There is a mismatch between your code and the code from the linked question. Your class does not extend a tkinter object. The class in the answer extended the tkinter Tk object like so:

class App(tk.Tk):

Thereby inheriting functions from the Tk class.

To solve this for your code, replace self in the process_serial function with a tkinter object, like self.textArea.

self.textArea.after(100, self.process_serial)

Alternatively, you could subclass tk.Tk just like in the linked answer. But I do not see the added benefit here.

Answer 2

The the method after was a inherited from Tkinter.Tk. Check mentioned question

You probably should subclass Tkinter.Tk

...
import Tkinter
class Gui(Tkinter.Tk)
    ...