Fix Python – How to make a python, command-line program autocomplete arbitrary things NOT interpreter

Question 1

I am aware of how to setup autocompletion of python objects in the python interpreter (on unix).

Google shows many hits for explanations on how to do this.
Unfortunately, there are so many references to that it is difficult to find what I need to do, which is slightly different.

I need to know how to enable, tab/auto completion of arbitrary items in a command-line program written in python.

My specific use case is a command-line python program that needs to send emails. I want to be able to autocomplete email addresses (I have the addresses on disk) when the user types part of it (and optionally presses the TAB key).

I do not need it to work on windows or mac, just linux.

Question 2

Use Python’s readline bindings. For example,

import readline

def completer(text, state):
    options = [i for i in commands if i.startswith(text)]
    if state < len(options):
        return options[state]
    else:
        return None

readline.parse_and_bind("tab: complete")
readline.set_completer(completer)

The official module docs aren’t much more detailed, see the readline docs for more info.

Question

Answer