The text widget insert method of tkinter not working

Question

I have been working on one application where in I want to autocomplete things like brackets round curly square. I had done that using the insert method of tkinter with the tk.INSERT constant as index like so:

def autocomplete(self, val) :
    if val == '(' :
        self.insert(tk.INSERT, ')')
    elif val == '{' :
        self.insert(tk.INSERT, '}')
    elif val == '[' :
        self.insert(tk.INSERT, ']')
    elif val == '\'' :
        self.insert(tk.INSERT, '\'')
        self.mark_set('sentinel', str(float(self.index(tk.INSERT)) - 0.1))
    elif val == '\"' :
        self.insert(tk.INSERT, '\"')
        self.mark_set('sentinel', str(float(self.index(tk.INSERT)) - 0.1))
    elif val == ':' :
        text = self.get(1.0, tk.INSERT).strip().replace(' ', '')
        
        if text[(text.index(':') - 1) : text.index(':')] == ')' :
            self.insert(tk.INSERT, '\n\t')
    return

This is a function which is within a text widget where the init has the following bindings attached:

self.bind('(', lambda x : self.autocomplete('('))
self.bind('{', lambda x : self.autocomplete('{'))
self.bind('[', lambda x : self.autocomplete('['))
self.bind(':', lambda x : self.autocomplete(':'))
self.bind('\'', lambda x : self.autocomplete('\''))
self.bind('\"', lambda x : self.autocomplete('\"'))

And when I type any of these like lets take the eg of brackets, then it shows the output somewhat not right.

)(

Here is also a snapshot of the same:

You see I want the other bracket to appear at the end but it does not.

Answer 1

This is because the binding is triggered before the character is inserted in the text widget. To fix this you can bind to '<KeyRelease-..>' instead, where .. needs to be replaced by the keysym.

self.bind('<KeyRelease-parenleft>', lambda x : self.autocomplete('('))
self.bind('<KeyRelease-braceleft>', lambda x : self.autocomplete('{'))
self.bind('<KeyRelease-bracketleft>', lambda x : self.autocomplete('['))
self.bind('<KeyRelease-colon>', lambda x : self.autocomplete(':'))
self.bind('<KeyRelease-apostrophe>', lambda x : self.autocomplete('\''))
self.bind('<KeyRelease-quotedbl>', lambda x : self.autocomplete('\"'))

The keysym of special characters are not always the same for all OS, so here is a trick to find the keysym of any key on your system:

import tkinter as tk
root = tk.Tk()
root.bind('<Key>', lambda ev: print(ev.keysym))
root.mainloop()

Just press the key to get the keysym