Listening to KeyPress and KeyRelease with Tkinter with debouncing

tkinter_key_event_debouncing.py

import Tkinter as tkinter

tk = tkinter.Tk()

has_prev_key_release = None

'''
When holding a key down, multiple key press and key release events are fired in
succession. Debouncing is implemented in order to squash these repeated events
and know when the "real" KeyRelease and KeyPress events happen.
'''

def on_key_release(event):
    global has_prev_key_release
    has_prev_key_release = None
    print "on_key_release", repr(event.char)

def on_key_press(event):
    print "on_key_press", repr(event.char)

def on_key_release_repeat(event):
    global has_prev_key_release
    has_prev_key_release = tk.after_idle(on_key_release, event)
    print "on_key_release_repeat", repr(event.char)

def on_key_press_repeat(event):
    global has_prev_key_release
    if has_prev_key_release:
        tk.after_cancel(has_prev_key_release)
        has_prev_key_release = None
        print "on_key_press_repeat", repr(event.char)
    else:
        on_key_press(event)

frame = tkinter.Frame(tk, width=100, height=100)
frame.bind("<KeyRelease-a>", on_key_release_repeat)
frame.bind("<KeyPress-a>", on_key_press_repeat)
frame.bind("<KeyRelease-s>", on_key_release_repeat)
frame.bind("<KeyPress-s>", on_key_press_repeat)
frame.pack()
frame.focus_set()

tk.mainloop()

because i wanted t make this generic i have modified your code to create a class:
https://github.com/JamesGKent/python-tkwidgets/blob/master/Debounce.py

so any tkinter widget can be subclassed to gain this functionality, with minimal code changes, as rather than changing the bindings and creating wrapper functions, all that need be changed is the widget definition, eg tk.Tk() changed to DebounceTk() where DebounceTk is declared as:

class DebounceTk(Debounce, tk.Tk):
    pass

Could you explain me how do these methods work? And why if I press the keys in quick succession, the program crashes, like a key was hold down forever?
Thank you

I don't see the advertized effect. Whenever I hold a key, I see repeated on_key_press messages instead of just one.

this doesnt work for me on python 3...