additional-tools.md

Additional Tools

Working with Python's virtual environments

virtualenvwrapper

The virtualenvwrapper package supports managing many virtual environments. See their documentation page for more information.

Standard library venv package

Since Python 3.3 the standard library contains the venv package supporting the creation of virtual environments. We recommend to create the virtual environment in the root directory of your project and naming it either .venv or venv (see The Hichhiker's Guide to Python).

Creating a virtual environment:

python -m venv .venv

Activate the virtual environment:

source .venv/bin/activate

Deactivate the virtual environment:

deactivate

Automatically activate and deactivate virtual environments

The following helper automatically activates a virtual environment when cd-ing into a directory with a accompanying virtual environment. For this to work, the virtual environment must be located in the root directory of your project and be named .venv or venv. Activation also works whe cd-ing into a subdirectory. Changing into a directory outside of your project's directory structure will automatically deactivate the virtual environment.

Add the following lines to your ~/.bashrc:

_update_path() {
  # Activate python virtualenv if '.venv' or 'venv' directory exists
  P=$(pwd)
  while [[ "$P" != / ]]; do
      if [[ -d "$P/.venv" && -f "$P/.venv/bin/activate" ]]; then
          if [[ "$P/.venv" != "$VIRTUAL_ENV" ]]; then
              source $P/.venv/bin/activate
          fi
          FOUND_VENV=yes
          break
      fi
      if [[ -d "$P/venv" && -f "$P/venv/bin/activate" ]]; then
          if [[ "$P/venv" != "$VIRTUAL_ENV" ]]; then
              source $P/venv/bin/activate
          fi
          FOUND_VENV=yes
          break
      fi
      P=$(dirname "$P")
  done
  if [[ "$FOUND_VENV" != yes && -v VIRTUAL_ENV ]]; then
      deactivate
  fi

  unset FOUND_VENV
  unset P
  true
}

cd() {
  builtin cd "$@"
  _update_path
}

_update_path

Automatic code formatting

Automate formatting using pre-commit

After registering hooks with install pre-commit will abort commits if there are black, isort or flake8 changes to be made. If machine fixable (ie. black and isort) pre-commit usually applies those changes leaving you to stage them using git add before retrying your commit.

pip install pre-commit
pre-commit install

Store the following configuration in .pre-commit-config.yaml:

repos:
  - repo: local
    hooks:
      - id: black
        name: black
        language: system
        entry: black
        types: [python]
      - id: isort
        name: isort
        language: system
        entry: isort -y
        types: [python]
      - id: flake8
        name: flake8
        language: system
        entry: flake8
        types: [python]

You can also run black, isort and flake8 on all content without comitting:

pre-commit run -a