Tkinter canvas not updating in an infinite loop

There are a number of issues with your code. One big one was the way you were updating the position of the existing canvas objects. The move() method needs to know the amount of movement (change in x and y value), not the new absolute position.

When I fixed that it turned out that the velocities were too big, so I reduced them to only be 10% of the values you had.

Another problem was with the way the ObjectHolder class was implemented. For one thing, the moveobject() method had no self argument, which it should have been using instead of having an object argument. You should probably also rename the method simply move().

The code below runs and does animate the movement.

import tkinter as tkclass ObjectHolder:    def __init__(self, pos, velocity, radius, id):        self.id = id                # the id of the canvas shape        self.pos = pos              # the position of the object        self.r = radius             # the radius of incluence of the object        self.velocity = velocity    # the velocity of the object    def moveobject(self):        x, y = self.pos        dx, dy = self.velocity        self.pos = (x + dx, y + dy)        canvas.move(self.id, dx, dy)  # Amount of movement, not new position.class App():    def __init__(self, canvas):        self.canvas = canvas        self.objects = []        for i in range(0, 2):            position = ((i+1)*100, (i+1)*100)#            velocity = (-(i+1)*10, -(i+1)*10)            velocity = (-(i+1), -(i+1))  # Much slower speed...            radius = (i + 1) * 20            x1 = position[0]-radius            y1 = position[1]-radius            x2 = position[0]+radius            y2 = position[1]+radius            id = canvas.create_oval(x1, y1, x2, y2)            self.objects.append(ObjectHolder(position, velocity, radius, id))        self.simulation(self.objects)    def simulation(self, objects):        for object in objects:             # this moves each object            object.moveobject()        # This part doesn't work. It is supposed to update the canvas        # and repeat forever.#        self.canvas.update()  # Not needed.#        root.update()  # Not needed.        self.canvas.after(50, self.simulation, objects)root = tk.Tk()canvas = tk.Canvas(root, width=800, height=600, bg="light blue")canvas.pack()app = App(canvas)root.mainloop()  # Added.