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

Follow the cmd documentation and you’ll be fine

import cmd

addresses = [
    '[email protected]',
    '[email protected]',
    '[email protected]',
]

class MyCmd(cmd.Cmd):
    def do_send(self, line):
        pass

    def complete_send(self, text, line, start_index, end_index):
        if text:
            return [
                address for address in addresses
                if address.startswith(text)
            ]
        else:
            return addresses


if __name__ == '__main__':
    my_cmd = MyCmd()
    my_cmd.cmdloop()

Output for tab -> tab -> send -> tab -> tab -> f -> tab

(Cmd)
help  send
(Cmd) send
[email protected]            [email protected]         [email protected]
(Cmd) send [email protected]
(Cmd)

Since you say “NOT interpreter” in your question, I guess you don’t want answers involving python readline and suchlike. (edit: in hindsight, that’s obviously not the case. Ho hum. I think this info is interesting anyway, so I’ll leave it here.)

I think you might be after this.

It’s about adding shell-level completion to arbitrary commands, extending bash’s own tab-completion.

In a nutshell, you’ll create a file containing a shell-function that will generate possible completions, save it into /etc/bash_completion.d/ and register it with the command complete. Here’s a snippet from the linked page:

_foo() 
{
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts="--help --verbose --version"

    if [[ ${cur} == -* ]] ; then
        COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
        return 0
    fi
}
complete -F _foo foo

In this case, the typing foo --[TAB] will give you the values in the variable opts, i.e. --help, --verbose and --version. For your purposes, you’ll essentially want to customise the values that are put into opts.

Do have a look at the example on the linked page, it’s all pretty straightforward.

Here is a full-working version of the code that was very supplied by ephemient here (thank you).

import readline

addrs = ['[email protected]', '[email protected]', '[email protected]']

def completer(text, state):
    options = [x for x in addrs if x.startswith(text)]
    try:
        return options[state]
    except IndexError:
        return None

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

while 1:
    a = raw_input("> ")
    print "You entered", a

# ~/.pythonrc
import rlcompleter, readline
readline.parse_and_bind('tab:complete')

# ~/.bashrc
export PYTHONSTARTUP=~/.pythonrc

I am surprised that nobody has mentioned argcomplete, here is an example from the docs:

from argcomplete.completers import ChoicesCompleter

parser.add_argument("--protocol", choices=('http', 'https', 'ssh', 'rsync', 'wss'))
parser.add_argument("--proto").completer=ChoicesCompleter(('http', 'https', 'ssh', 'rsync', 'wss'))

The posted answers work fine but I have open sourced an autocomplete library that I wrote at work. We have been using it for a while in production and it is fast, stable and easy to use. It even has a demo mode so you can quickly test what you would get as you type words.

To install it, simply run: pip install fast-autocomplete

Here is an example:

>>> from fast_autocomplete import AutoComplete
>>> words = {'book': {}, 'burrito': {}, 'pizza': {}, 'pasta':{}}
>>> autocomplete = AutoComplete(words=words)
>>> autocomplete.search(word='b', max_cost=3, size=3)
[['book'], ['burrito']]
>>> autocomplete.search(word='bu', max_cost=3, size=3)
[['burrito']]
>>> autocomplete.search(word='barrito', max_cost=3, size=3)  # mis-spelling
[['burrito']]

Checkout: https://github.com/seperman/fast-autocomplete for the source code.

And here is an explanation of how it works: http://zepworks.com/posts/you-autocomplete-me/

It deals with mis-spellings and optionally sorting by the weight of the word. (let’s say burrito is more important than book, then you give burrito a higher "count" and it will show up first before book in the results.

Words is a dictionary and each word can have a context. For example the "count", how to display the word, some other context around the word etc. In this example words didn’t have any context.

You can try using the Python Prompt Toolkit, a library for building interactive command line applications in Python.

The library makes it easy to add interactive autocomplete functionality, allowing the user to use the Tab key to visually cycle through the available choices. The library is cross-platform (Linux, OS X, FreeBSD, OpenBSD, Windows). Example:

(Image source: pcgli)

This works well.

#!/usr/bin/python3

import readline
readline.parse_and_bind("tab: complete")

def complete(text,state):
    volcab = ['dog','cat','rabbit','bird','slug','snail']
    results = [x for x in volcab if x.startswith(text)] + [None]
    return results[state]

readline.set_completer(complete)

line = input('prompt> ')