Custom tab completion in python argparse

Question

How to get shell tab completion cooperating with argparse in a Python script?

#!/usr/bin/env python         


        

Answer 1

For auto-complete to work you need a bash function to generate the possible options, and then you need to run complete -F

The best way of doing this is to have the program generate the completion function based on it's own parsing algorithm to avoid duplication. However, at a quick glance on argparse, I could not find a way to access it's internal structure, but I suggest you look for it.

Here is a bash function that will do for the above program:

function _example_auto() {
    local cur=${COMP_WORDS[COMP_CWORD]}
    local prev=${COMP_WORDS[COMP_CWORD-1]}

    case "$prev" in
    --optional ) 
        COMPREPLY=( $(compgen -W "foo1 foo2 bar" -- $cur) )
        return 0
        ;;
    *)
        COMPREPLY=( $(compgen -W "--optional spam eggs" -- $cur) )
        return 0
        ;;
    esac
}