Question

I’m new to programming and I can’t understand how garbage collection works. In the following example:

import Tkinter as tk

a = 0

class Object1:

    def __init__(self):
        global a
        a = tk.Frame()
        a.pack()
        b = tk.Button(a, text="click me", command=self.callback)
        b.pack()

    def callback(self):
        print "clicked!"
        program = Object2()

class Object2:

    def __init__(self):
        global a
        a.destroy()
        a2 = tk.Frame()
        a2.pack()
        b = tk.Label(a2, text='This is the second object.')
        b.pack()



program = Object1()

tk.mainloop()

Does ‘program,’ the instance of Object1, remain at the end? Do I have to explicitly delete it somehow? If I repeat this structure many times, with each Objectx having a button that destroys the previous frame and adds a new frame with new content, will that consume more and more memory as the program proceeds? Thanks for any help.

Answer 1

a will reference a “destroyed” tk.Frame

To allow the tk.Frame to be garbage collected you need to remove that reference to it

One way is to set a = None another way would be to del a

Of course when the program actually ends everything is freed