pycomplete

A Python library to generate static completion scripts for your CLI app

Installation

pycomplete requires Python 3.6 or higher, you can install it via PyPI:

$ pip install pycomplete

Usage

With pycomplete, one can generate a completion script for CLI application that is compatible with a given shell. The script outputs the result onto stdout, allowing one to re-direct the output to the file of their choosing.

pycomplete accepts different types of objects depending on which CLI framework you are using. For argparse, argparse.ArgumentParser is expected while for click, either click.Command or click.Context is OK. pycomplete knows what to do smartly.

Where you place the file will depend on which shell, and which operating system you are using. Your particular configuration may also determine where these scripts need to be placed.

Note that pycomplete needs to be installed in the same environment as the target CLI app to work properly.

Here are some common set ups for the three supported shells under Unix and similar operating systems (such as GNU/Linux).

BASH

Completion files are commonly stored in /etc/bash_completion.d/. Run command:

$ pycomplete "myscript:parser" bash > /etc/bash_completion.d/_myscript

You may have to log out and log back in to your shell session for the changes to take effect.

FISH

Fish completion files are commonly stored in$HOME/.config/fish/completions/. Run command:

$ pycomplete "myscript:parser" fish > $HOME/.config/fish/completions/myscript.fish

You may have to log out and log back in to your shell session for the changes to take effect.

ZSH

ZSH completions are commonly stored in any directory listed in your $fpath variable. To use these completions, you must either add the generated script to one of those directories, or add your own to this list.

Adding a custom directory is often the safest best if you're unsure of which directory to use. First create the directory, for this example we'll create a hidden directory inside our $HOME directory

$ mkdir ~/.zfunc

Then add the following lines to your .zshrc just before compinit

$ fpath+=~/.zfunc

Run command:

$ pycomplete "myscript:parser" zsh > ~/.zfunc/_myscript

You must then either log out and log back in, or simply run

$ exec zsh

For the new completions to take affect.

Powershell

There is no default location for completion scripts on Powershell. One may need to execute the scripts in their profile:

PS > mkdir $PROFILE\..\Completions
PS > echo @'
Get-ChildItem "$PROFILE\..\Completions\" | ForEach-Object {
    . $_.FullName
}
'@ | Out-File -Append -Encoding utf8 $PROFILE

Make sure you set the proper Execution Policy:

PS > Set-ExecutionPolicy Unrestricted -Scope CurrentUser

Run command to generate script:

PS > pycomplete "myscript:parser" powershell | Out-File -Encoding utf8 $PROFILE\..\Completions\myscript_completion.ps1

You may have to log out and log back in to your shell session for the changes to take effect.

CUSTOM LOCATIONS

Alternatively, you could save these files to the place of your choosing, such as a custom directory inside your $HOME. Doing so will require you to add the proper directives, such as sourceing inside your login script. Consult your shells documentation for how to add such directives.

Integrate with existing CLI apps

pycomplete can be also used as a Python library, allowing one to integrate with existing CLI apps.

from pycomplete import Completer
from mypackage.cli import parser

completer = Completer(parser)
print(completer.render())

See examples/ folder for full examples of working apps.

How does it differ from argcomplete?

argcomplete, together with click-completion, can also generate scripts for shell completion. However, they work in a different way that commands and options are retrieved on the fly when they are requested by a matching token. This brings a performance shrinkage when it is expensive to import the CLI app. In the other side, pycomplete produces static and fixed scripts which contain all required information within themselves. Plus, argcomplete and click-completion both work for specific framework. One may notice the disadvantage of static completion is also obvious -- users must regenerate the script when the commands and/or options are updated. Fortunately, it shouldn't be a problem in most package managers like homebrew, where completion scripts are part of the package and are bundled with it.

Limitations

Only options and subcommands are autocompleted, positional arguments are not completed since user usually expects the path sugguestion to work in this case.

Supported CLI Frameworks

• argparse.ArgumentParser
• click.Command, click.Context
• More to be added