Making a flashing text in tinker - python-3.x

Question

I want a text that flashes with a clock's seconds. This Link was helpful, but couldn't solve my problem. Below is my little working code:
from tkinter import *
from datetime import datetime
import datetime as dt
import time
def change_color():
curtime=''
newtime = time.strftime('%H:%M:%S')
if newtime != curtime:
curtime = dt.date.today().strftime("%B")[:3]+", "+dt.datetime.now().strftime("%d")+"\n"+newtime
clock.config(text=curtime)
clock.after(200, change_color)
flash_colours=('black', 'red')
for i in range(0, len(flash_colours)):
print("{0}".format(flash_colours[i]))
flashing_text.config(foreground="{0}".format(flash_colours[i]))
root = Tk()
clock = Label(root, text="clock")
clock.pack()
flashing_text = Label(root, text="Flashing text")
flashing_text.pack()
change_color()
root.mainloop()
This line of code: print("{0}".format(flash_colours[i])) prints the alternating colors on the console as the function calls itself every 200s. But the flashing_text Label's text foreground doesn't change colors.
Does anybody have a solution to this problem? Thanks!
Please forgive my bad coding.

Answer 1

Although you have changed the color of the flashing_text in the for loop twice, but the tkinter event handler (mainloop()) can only process the changes when it takes back the control after change_color() completed. So you can only see the flashing_text in red (the last color change).
To achieve the goal, you need to change the color once in the change_color(). Below is a modified change_color():
def change_color(color_idx=0, pasttime=None):
newtime = time.strftime('%H:%M:%S')
if newtime != pasttime:
curtime = dt.date.today().strftime("%B")[:3]+", "+dt.datetime.now().strftime("%d")+"\n"+newtime
clock.config(text=curtime)
flash_colors = ('black', 'red')
flashing_text.config(foreground=flash_colors[color_idx])
clock.after(200, change_color, 1-color_idx, newtime)

Answer 2

I would add it to a class so you can share your variables from each callback.
So something like this.
from tkinter import *
from datetime import datetime
import datetime as dt
import time
class Clock:
def __init__(self, colors):
self.root = Tk()
self.clock = Label(self.root, text="clock")
self.clock.pack()
self.flashing_text = Label(self.root, text="Flashing text")
self.flashing_text.pack()
self.curtime = time.strftime('%H:%M:%S')
self.flash_colours = colors
self.current_colour = 0
self.change_color()
self.root.mainloop()
def change_color(self):
self.newtime = time.strftime('%H:%M:%S')
if self.newtime != self.curtime:
if not self.current_colour:
self.current_colour = 1
else:
self.current_colour = 0
self.curtime = time.strftime('%H:%M:%S')
self.flashing_text.config(foreground="{0}".format(self.flash_colours[self.current_colour]))
self.clock.config(text=self.curtime)
self.clock.after(200, self.change_color)
if __name__ == '__main__':
clock = Clock(('black', 'red'))