Not deleting leading characters python tkinter

Question

How would i go about setting up a Tkinter Text widget to do something similar to IDLE's entry? For example:

>>> Entry goes here!

However, i know how to insert them at the beginning of each line, but how would i go about making it non deletable, so that you cannot delete the >>>? I have searched around on google about this, but to no avail.

Answer 1

If the solution only has to be "Good Enough", the technique I would use is this:

1. When you insert the prompt, remember the index of the end of the prompt.
2. Add a binding to the widget for the events you care about (eg: <BackSpace> and <Delete> and <<Cut>>)
3. In this binding you can look at the index of the insertion cursor and selection, and if it's prior to the saved index, ignore the event (ie: do a return "break").

This should work more-or-less OK, though it allows you to insert characters prior to the prompt. Rewriting all the bindings that alter a text widget is a fairly daunting task, but just tracking deletes isn't too hard.

To solve the problem perfectly would require you write a little tcl code to intercept the low level insert and delete commands of the actual widget. It's possible, though it requires a decent understanding of the underlying tcl code. For an example, see this answer: https://stackoverflow.com/a/11180132/7432