Python3 tkinter text entry widget with built-in autocompletion class, with working example (revised version)

autocomplete.py

#!/usr/bin/python3

"""
tkentrycomplete.py

A tkinter widget that features autocompletion.

Created by Mitja Martini on 2008-11-29.
Converted to Python3 by Ian weisser on 2014-04-06.
Edited by Victor Domingos on 2016-04-25.
"""

import sys
import os
import tkinter

__version__ = "1.0.1"

tkinter_umlauts=['odiaeresis', 'adiaeresis', 'udiaeresis', 'Odiaeresis', 'Adiaeresis', 'Udiaeresis', 'ssharp']


class AutocompleteEntry(tkinter.Entry):
    """
    Subclass of tkinter.Entry that features autocompletion.

    To enable autocompletion use set_completion_list(list) to define 
    a list of possible strings to hit.
    To cycle through hits use down and up arrow keys.
    """

    def set_completion_list(self, completion_list):
        self._completion_list = completion_list
        self._hits = []
        self._hit_index = 0
        self.position = 0
        self.bind('<KeyRelease>', self.handle_keyrelease)               

    def autocomplete(self, delta=0):
        """autocomplete the Entry, delta may be 0/1/-1 to cycle through possible hits"""
        if delta: # need to delete selection otherwise we would fix the current position
            self.delete(self.position, tkinter.END)
        else: # set position to end so selection starts where textentry ended
            self.position = len(self.get())
        # collect hits
        _hits = []
        for element in self._completion_list:
            if element.lower().startswith(self.get().lower()):
                _hits.append(element)

        # if we have a new hit list, keep this in mind
        if _hits != self._hits:
            self._hit_index = 0
            self._hits=_hits
        # only allow cycling if we are in a known hit list
        if _hits == self._hits and self._hits:
            self._hit_index = (self._hit_index + delta) % len(self._hits)
        # now finally perform the auto completion
        if self._hits:
            self.delete(0, tkinter.END)
            self.insert(0,self._hits[self._hit_index])
            self.select_range(self.position,tkinter.END)
                        
    def handle_keyrelease(self, event):
        """event handler for the keyrelease event on this widget"""
        if event.keysym == "BackSpace":
            if self.position < self.index(tkinter.END): # delete the selection
                self.delete(self.position, tkinter.END)
            else:
                self.position = self.index(tkinter.END)
        if event.keysym == "Left":
            if self.position < self.index(tkinter.END): # delete the selection
                self.delete(self.position, tkinter.END)
        if event.keysym == "Right":
            self.position = self.index(tkinter.END) # go to end (no selection)
        if event.keysym == "Down":
            self.autocomplete(1) # cycle to next hit
        if event.keysym == "Up":
            self.autocomplete(-1) # cycle to previous hit
        # perform normal autocomplete if event is a single key or an umlaut
        if len(event.keysym) == 1:
            self.autocomplete()
            

def test(test_list):
    """Run a mini application to test the AutocompleteEntry Widget."""
    root = tkinter.Tk(className=' AutocompleteEntry demo')
    entry = AutocompleteEntry(root)
    entry.set_completion_list(test_list)
    entry.pack()
    entry.focus_set()
    root.mainloop()
    

if __name__ == '__main__':
    test_list = (u'test', u'type', u'true', u'tree', u'tölz')
    print("Type a 't' to test the AutocompleteEntry widget.")
    print("Will use AutocompleteEntry.set_completion_list({})".format(test_list))
    print("Try also the backspace key and the arrow keys.")
    test(test_list)