Introduction

The Fish shell is renowned for its user-friendly nature, making it an ideal command-line interface for macOS, Linux, and more. The shell stands out with its unique features, including auto-completion, syntax highlighting, and tabbed completion. Additionally, its learning curve is gentle enough for beginners to grasp quickly.

Despite these attractive attributes, many developers I've come across don't prefer Fish shell, primarily due to integration gaps with tools like Python's virtualenv. So, in this article, I'm offering a simple solution for automatic virtualenv activation for Fish shell, steering clear of resource-intensive frameworks like oh-my-fish that often slow down the shell.

Understanding Python's Virtualenv

Python's virtualenv is a tool that creates isolated Python environments, making it an invaluable resource for managing project dependencies and testing Python's new versions without affecting the system's main installation.

It is perplexing and perhaps not ideal to have Python's dependencies installed globally instead of project-specific folders. This issue necessitates workarounds such as virtualenv.

The Objective

Before diving into the solution, let's clearly define our goal.

Task

We aim to automate the activation of virtualenv when we navigate into the project folder or any of its sub-folders. Additionally, we want to deactivate virtualenv when exiting the project's scope.

A bottom-up search for the virtualenv folder is crucial as multiple virtualenvs can reside within the project folder, and we need to use the nearest one.

The ultimate goal is to devise a minimalist solution to minimize performance hindrances and ensure maximum compatibility with any Fish environment.

Solution: An Adapted Plugin

I adapted the code from timothybrown/fish-autovenv, originally created by Timothy Brown, and published the modified version on GitHub.

The existing solution had a few shortcomings:

• It was incompatible with newer versions of Fish, and my goal was to retain simplicity.
• The plugin for created for oh-my-fish, which is a resource-intensive framework that slows down the shell.
• The plugin could only detect virtual environments in the current directory, not in specified sub-directories. For instance, I store my virtual environments in a .venv sub-directory.
• The plugin didn't apply the virtual environment when opening a terminal in a directory containing a custom virtual environment.
• It searched for virtualenvs top-down (/home, /home/user, /home/user/projects, /home/user/projects/pytest), whereas a bottom-up approach would have been more efficient and user-friendly.

As a minimalist plugin manager for Fish, I recommend fisher. I've created a plugin that can be installed via fisher and integrated into any Fish environment. If there are any reasons why you don't want to use Fisher, you can just copy-paste conf.d/autoenv.fish file to your ~/.config/fish/conf.d directory.

The project can be found here: aohorodnyk/fish-autovenv.

Installation

To install aohorodnyk/fish-autovenv, by using fisher:

fisher install aohorodnyk/fish-autovenv

The plugin offers several configurable settings for a tailored user experience:

• set -U autovenv_enable yes|no - to enable or disable the plugin (enabled by default).
• set -U autovenv_announce yes|no - to enable or disable announcements when virtualenv is activated or deactivated (enabled by default).
• set -U autovenv_dir '.venv' - to specify the name of the directory where virtualenv is located (default is .venv).

Conclusion

Don't be apprehensive about using the Fish shell. It's a versatile, fast, and intuitive shell, making it a worthy alternative to bash and zsh.

Contributing to open-source is an excellent way to learn, help others, and contribute to making the technological world better and simpler for everyone.