A subclass of Tkinters Entry class that allows for dynamic sizing. Assign a delegate, ensure callback is implemented and set offset to desired value to extend to (such as 2 * text length)

resizableentry.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import Tkinter as Tk
 
class ResizeableEntry(Tk.Entry):
    """
    Class that adds resizing functionality to the Tkinter Entry class.
    Makes callbacks to the delegate on whether it should resize and how much it should.
    """
    def __init__(self, parent=None, delegate=None, **options):
        Tk.Entry.__init__(self, parent, **options)
        self.delegate = delegate
 
    def pack(self, **options):
        """
        Override packing function to acquire all the pack options.
        """
        Tk.Entry.pack(self, **options)
 
        if not hasattr(self, 'defaultPackOptions'):
            # Only set default pack options once
            self.defaultPackOptions = options
            
    def resize(self, offset=0):
        try:
            # Ask the delegate if it should resize the entry
            if self.delegate.should_resize():
                # Resize the default pack options if there 
                # is an offset and subtract after applying offset
                # to avoid overgrowing
                self.defaultPackOptions['ipadx'] += offset 
                self.pack(**self.defaultPackOptions)
                self.defaultPackOptions['ipadx'] -= offset
            
        except AttributeError:
            print "No delegate exists for ResizeableEntry object %d." % id(self)

Bless