Python tkinter text modified callback

Question

In python 2.7, I am trying to get a callback every time something is changed in the Tkinter Text widget.

The program uses multiple frames based on code found here:

Answer 1

I integrated the above <>> example in my code and it worked quite well, except that it was interfering with some edit_modified() commands.

Fortunately, the tkinter Text window has a poorly documented feature which is as good and is fully compatible with the edit_modified() get or set commands: the predefined <>> tag. You don't even have to create it, it works out-of-the-box.

Here are the relevant parts of my code:

The "self" prefixes were removed, some adjustments may be needed

Put that in your Text gadget code:

title = set_title(fname, numbr)

text.bind("<>", lambda dummy: save_indicator(title))

Make sure these functions are visible:

def set_title(fname, numbr):  
    "Creates a window title showing the save indicator,"  
    "the file name and a window number"  
    fname = strip_path(fname)  
    if not fname:  
        fname = "(New Document)"  
    return "+ {} - Window no.{}".format(fname, numbr)  

def strip_path(fname):  
    return os.path.split(fname)[-1]

def save_indicator(title, event=None):  
    "Update the window title"  
    titre = toggle_star(title)  
    text.winfo_toplevel().title(title)  

def toggle_star(title):  
    "Change the first character of the title"  
    chr='+'; chr0='x'  
    if text.edit_modified():  
        title = chr0 + title[1:]  
    else:  
        title = chr + title[1:]  
    return title  

Here is a complete working example with the predefined <>> tag:

def toggle_star(title):  
    "Change the color of the star in the title bar"  
    chr='+'; chr0='x'  
    if text.edit_modified():  
            title = chr0 + title[1:]  
    else:  
            title = chr + title[1:]  
    return title  

def set_title(fname, winno):  
    "Put save indicator, file name and window number in the title"  
    if not fname:  
            fname = "(New Document)"  
    return "+ {} - Window no.{}".format(fname, winno)  

def mockSave(title, event=None):  
    title = toggle_star(title)  
    root.winfo_toplevel().title(title)  
    text.edit_modified(0)  

def read_ed_mod():  
    print("text.edit_modified()=", text.edit_modified())  

def onModification(title, event=None):  
    title = toggle_star(title)  
    root.winfo_toplevel().title(title)  

from tkinter import *  

fname = 'blabla.txt'  
winno = 1 ;  

root = Tk()  
label = Label(root, anchor="w")  
text = Text(root, width=40, height=4)  
label.pack(side="bottom", fill="x")  
text.pack(side="top", fill="both", expand=True)  
Button(root, text='Mock Save', command= lambda: mockSave(title)).pack(side=LEFT)  
Button(root, text='Read ed_mod', command= lambda: read_ed_mod()).pack(side=RIGHT)  
text.bind('<>', lambda event: onModification(title))  

title = set_title(fname, winno)  
root.winfo_toplevel().title(title)  
text.edit_modified(0)  

root.mainloop()