[FIXED] need to reverse tk textbox widget event/handler priority - python

Issue

I have a textbox widget that has 2 event bindings like so:

F2_text_editor.bind('<Return>', lambda e: on_key_release())
F2_text_editor.bind("<BackSpace>", lambda e: on_key_release(), add="+")

I am working on adding line numbers to my text editor. All is well so far but the last issue I have encountered is not one I think is fixable?

Basically what is happening is that when I press either binded key on my keyboard its executed the function, then completes the action from the keyboard itself.

For example let's say I have a binding and a function that prints out a message. When I hit Return, it will print out the message and then move the cursor to the next line. Is there a way to reverse this?

Here the code:

def on_key_release():
    print("on_key_release")
    #F2_line_numbers.delete("1.0", "end")

    final_index = str(F2_text_editor.index("end-1c"))
    print(f"final_index: {final_index}")

    num_of_lines = final_index.split('.')[0]
    print(f"num_of_lines: {num_of_lines}")

    line_numbers_string = "\n".join(str(no + 1) for no in 
    range(int(num_of_lines)))
    #print(f"line_numbers_string: {line_numbers_string}")

    width = len(str(num_of_lines))
    #print(f"width: {width}")

    F2_line_numbers.configure(state='normal', width=width)
    F2_line_numbers.delete("1.0", "end")
    F2_line_numbers.insert("1.0", line_numbers_string)
    F2_line_numbers.configure(state='disabled')

The reason I need to reverse the 'event/handler' priority is because when I am on line 1 for example and hit Return, that function prints out 'index 1.0 / num of line: 1' when I am on line 2. Then I hit Backspace and it says I am on line 2 when I am on line 1.

UPDATE: I thought I would try and add a wait to the handler function but all it did was force the event to wait till the handler had been executed. Another feature I am working on also needs the event/handler priority to be reversed too so I am really hoping someone knows how to do this.

Solution

I solved this by using threading.

The function binded to the widget contains a thread to another function that handles the line number think. Now when I am on line 1 and hit enter it shows line 2. I then hit backspace and it shows line 1 just as it should. Threading is allowing the event to occur before the function which is exactly what I wanted.

Answered By - phil