This is the sort of tool that experienced devs all use, but nobody teaches or writes it into a tutorial on the larger language as a whole, because it feels like a side tool.
For now I'm not seeing a lot of reasons to use PyEnv over the `venv` module that ships with Python 3.3+ [1]. I'm sure there are some thing PyEnv does that `venv` doesn't, but the fact that `venv` ships with Python greatly simplifies things.
Basically my workflow is:
1. I'll create a Python project with, `mkdir dirname`, `cd dirname`, `git init`, `python3 -m venv .env`. This creates a hidden folder named `.env/` which contains the virtual environment. I'll then usually add `.env/` to my `.gitignore`, and also run `pip install --upgrade pip` and `pip install wheel`.
2. If I'm using an existing project, I'll do `git clone `projname`, `cd dirname`, `python3 -m venv .env`, `pip install -m requirements.txt` (requirements.txt is the idiomatic name for the dependencies list in Python projects).
3. I have the following lines in my `~/.bashrc` (hidden file that contains Bash settings):
# Gets a directory named .env or .venv if it exists in the currend directory or any of its parents
get_env() {
if [ -d "$1/.env" ] ; then
echo "$1/.env"
else
if [ -d "$1/.venv" ] ; then
echo "$1/.venv"
else
if [ -d "$1/.." ] ; then
get_env "$1/.."
fi
fi
fi
}
get_absolute_path() {
python3 -c "import os; print(os.path.realpath('$1'))"
}
on_prompt() {
# Load a virtualenv environment if it exists in a file named .env
env_folder=$(get_env $(pwd))
if [ -d "$env_folder" ] ; then
if [[ $VIRTUAL_ENV != $(get_absolute_path $env_folder) ]] ; then
echo "Activating env '$env_folder'"
source "$env_folder/bin/activate"
fi
else
if [ -d "$VIRTUAL_ENV" ] ; then
deactivate
fi
fi
}
# Call on_prompt() every time the command prompt executes
PROMPT_COMMAND=on_prompt
What this does is when I `cd` or `pushd` into a directory or subdirectory of a directory that contains a `.env/` folder, it loads the virtual environment, and when I leave said directories, it exits the virtual environment.
4. When I install a dependency, I use `pip freeze` to get the dependency string, and I append that line to the file `requirements.txt`. For example, if I do `pip install django`, I get `Django==5.0.1` in my output from `pip freeze`, so I'll append that line to my `requirements.txt`.
5. To upgrade dependencies, I edit the version number in the `requirements.txt` file, and then run `pip install -m requirements.txt`. This makes sure that the requirements file stays up-to-date with my locally installed dependencies.
6. To get valid version numbers for a file, you can do `pip install ==`, which is basically asking pip to install an invalid version number. This causes it to list valid version numbers. For example, you can do `pip install django==` to view all available Django versions.
[1] https://docs.python.org/3/library/venv.html