from tkinter import *
root = Tk()
sv = StringVar()
def callback():
print(sv.get())
return True
e = Entry(root, textvariable=sv, validate="focusout", validatecommand=callback)
e.grid()
e = Entry(root)
e.grid()
root.mainloop()
from Tkinter import *
def callback(sv):
print sv.get()
root = Tk()
sv = StringVar()
sv.trace("w", lambda name, index, mode, sv=sv: callback(sv))
e = Entry(root, textvariable=sv)
e.pack()
root.mainloop()
sv.trace_add("write", callback)