pyzshcomplete 1.0.3

Tab completion for arbitraty python scripts in zsh

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Tab completion for arbitraty python scripts in zsh.

Introduction

This project was inspired by argcomplete, which supplies argument completion for bash.

While having a workaround for zsh (which just enables compatibility for bash completion scripts), argcomplete can’t use the full power of the zsh completion system (e.g. show flag help messages).

pyzshcomplete was written to utilize as many of the features offered by zsh as possible.

Prerequisites

In order for completion to work in zsh, the autocompletion module must be enabled. If you are using Oh My Zsh, this is probably already the case. Otherwise, please refer to the zsh manual for more details, or Just Google It™ since it will probably be easier.

Installation

pip install pyzshcomplete
~/.local/bin/activate_pyzshcomplete

Restart zsh after the installation is complete.

NOTE 1: The path to activate_pyzshcomplete will differ depending on where pip installs packages, and it may not be in your PATH, so you will have to find it.

Note 2: Removing the package will leave residual files in your system. This is currently unavoidable, since pip is not aware of these files. For those who want to clean up their system, take a look at the source of activate_pyzshcomplete

Usage

To emphasize the similarity to argcomplete, here is the example usage shown in the argcomplete readme:

#!/usr/bin/env python
# PYTHON_ARGCOMPLETE_OK
import argcomplete, argparse
parser = argparse.ArgumentParser()
...
argcomplete.autocomplete(parser)
args = parser.parse_args()
...

And here it is adapted to pyzshcomplete:

#!/usr/bin/env python
# PYZSHCOMPLETE_OK
import pyzshcomplete, argparse
parser = argparse.ArgumentParser()
...
pyzshcomplete.autocomplete(parser)
args = parser.parse_args()
...

Note that the magic string PYZSHCOMPLETE_OK is required to appear at the top of the script. This is similar to the PYTHON_ARGCOMPLETE_OK magic of argcomplete.

The autocomplete(parser) method

This method is the interface to the autocompletion mechanism. It must be called after the parser construction is complete, but before the arguments are parsed.

It receives your parser as an argument, converts it to a zsh completion script format passes it on and exits the python program. The output is then used by the zsh completion system to generate completions.

The consequences are that your program is actually being run as part of argument completion and anything you do prior to calling autocomplete will happen every time the user attempts autocompletion. Additionally, if it takes a long time for the program to reach autocomplete, this time will be reflected as a lag that the user will experience.

Can I use both argcomplete and pyzshcomplete?

TL;DR: Yes!

example:

#!/usr/bin/env python3
# PYTHON_ARGCOMPLETE_OK
# PYZSHCOMPLETE_OK

from argparse import ArgumentParser
import pyzshcomplete, argcomplete

parser = ArgumentParser()
parser.add_argument('arg')

# These lines can be in any order
argcomplete.autocomplete(parser)
pyzshcomplete.autocomplete(parser)

args = parser.parse_args()

Both argcomplete and pyzshcomplete use an environment variable set by the completion script that is unique to that shell. If that variable is not set, the autocomplete function simply returns without doing anything.

argcomplete uses _ARGCOMPLETE and pyzshcomplete uses PYZSHCOMPLETE. this means that if you’re using bash, the _ARGCOMPLETE environment variable will be set, and only argcomplete.autocomplete will do completion magic, and vice versa if you’re using zsh.

Smart Completion

zsh offers easy ways to complete things such as process ids, user accounts, network interfaces, bookmarks and more.

As of this moment, there is no mechanism that enables associating an argument with these options. Stay tuned, as it is a prioritized feature.

Supported Parsers

pyzshcomplete was written to be easy to extend for new parsers. It currently supports only argparse, but you are welcome to request or contribute support for other parsers.

Non-Supported Features

Some features of certain parsers can’t be (easily enough) supported by zsh or pyzshcomplete and are listed here for public knowledge.

General

• Completion for python modules (python -m <module>)

Argparse

• Subparsers - Subparsers will be supported in the near future.

• Custom actions - There is no way to know in advance what effect will actions have on the way the argument should be supplied (e.g. can a flag be specified multiple times?).

• Non-standard flag prefixes - Only the - and + prefixes are supported, as that is what the _arguments completion utility supports.

• Usage of the from_file_prefix_chars in ArgumentParser

Python Support

Official support is for Python 3 only.

Feature Requests and Bug Reports

Feature requests and bug reports are tracked on Github.

Resources

Getting into zsh internals isn’t easy. If you are interested to learn more of the inner workings, take a look at the following resources:

• From Bash to Z Shell - This book is intended to teach zsh by example, and is much more easy to read than any manual or user guide I’ve encountered (You can find the full pdf in a simple search, but I didn’t tell you that).

• The Zsh Manual - After you’ve acquainted yourself with the basics, and want the full spec of anything particular, this is the document to go to.

• Zsh Reference Card - After you know what you’re doing, you can use this reference card for quick reminders.

License

Licensed under the terms of the MIT License.