Configure Python develop tool chain

- use pyenv to manage the develop environments
  + install several Python versions (3.7 - 3.10 and 2.7)
  + each version receives its own copies of black, pipenv, and poetry
- add two more virtual environments based off the latest version:
  + "interactive" => default environment optimized for interactive
                     usage with with black, bpython, and ipython
                     (also receives accidental `pip install`s)
  + "utils" => hosts various globally available tools/apps
               (e.g., mackup and youtube-dl)
- add installation and update scripts for the entire tool chain
- set up completions for bash and zsh
- set up convenient aliases
- configure bpython
- configure poetry

.config/shell/aliases.sh

@@ -86,6 +86,25 @@ alias more='less'
 alias tree='tree -C --dirsfirst'
 
 
+# Make working with Python more convenient
+
+# Interactive shells
+alias py='python'
+alias bpy='bpython'
+alias ipy='ipython'
+
+if _command_exists poetry; then
+    alias pr='poetry run'
+fi
+
+if _command_exists pyenv; then
+    alias pyvenvs='pyenv virtualenvs --bare --skip-aliases'
+    alias pyver='pyenv version'
+    alias pyvers='pyenv versions --skip-aliases'
+    alias pywhich='pyenv which'
+fi
+
+
 # Various one-line utilities
 alias datetime='date +"%Y-%m-%d %H:%M:%S %z (%Z)"'
 alias datetime-iso='date --iso-8601=seconds'

.config/shell/utils.sh

@@ -9,6 +9,15 @@ _in_zsh() {
     [ -n "$ZSH_VERSION" ]
 }
 
+prepend-to-path () {  # if not already there
+    if [ -d "$1" ] ; then
+        case :$PATH: in
+            *:$1:*) ;;
+            *) PATH=$1:$PATH ;;
+        esac
+    fi
+}
+
 
 
 # Configure the keyboard:
@@ -19,6 +28,16 @@ _command_exists xcape && xcape -e "Caps_Lock=Escape"
 
 
 
+_init_pyenv () {  # used further below as well
+    _command_exists pyenv || return
+
+    eval "$(pyenv init -)"
+    eval "$(pyenv virtualenv-init -)"
+}
+_init_pyenv
+
+
+
 # ==============================
 # Working with files and folders
 # ==============================
@@ -174,6 +193,94 @@ genemail() {
 
 
 
+# ===================================================
+# Set up & maintain the Python (develop) environments
+# ===================================================
+
+
+# TODO: This needs to be updated regularly (or find an automated solution)
+# The Python versions pyenv creates (in descending order
+# Important: The first version also holds the "interactive" and "utils" environments)
+_py3_versions=('3.10.6' '3.9.13' '3.8.13' '3.7.13')
+_py2_version='2.7.18'
+
+# Each Python version receives its own copy of black, pipenv, and poetry
+# (e.g., to avoid possible integration problems between pyenv and poetry
+#  Source: https://github.com/python-poetry/poetry/issues/5252#issuecomment-1055697424)
+_py3_site_packages=('black' 'pipenv' 'poetry')
+
+# The pyenv virtualenv "utils" contains some globally available tools (e.g., mackup)
+_py3_utils=('mackup' 'youtube-dl')
+
+# Important: this REMOVES the old ~/.pyenv installation
+_install_pyenv() {
+    echo "(Re-)Installing pyenv"
+
+    # Ensure that pyenv is on the $PATH
+    # (otherwise, the pyenv installer emits warnings)
+    mkdir -p "$PYENV_ROOT/bin"
+    prepend-to-path "$PYENV_ROOT/bin"
+
+    # Remove old pyenv for clean install
+    rm -rf "$PYENV_ROOT" >/dev/null
+
+    # Run the official pyenv installer
+    curl https://pyenv.run | bash
+
+    # Make pyenv usable after this installation in the same shell session
+    _init_pyenv
+}
+
+create-or-update-python-envs() {
+    _command_exists pyenv || _install_pyenv
+
+    eval "$(pyenv init --path)"
+
+    # Keep a legacy Python 2.7, just in case
+    echo "Installing/updating Python $_py2_version"
+    pyenv install --skip-existing $_py2_version
+    pyenv rehash  # needed on a first install
+    PYENV_VERSION=$_py2_version pip install --upgrade pip setuptools
+    PYENV_VERSION=$_py2_version python -c "import sys; print sys.version"
+
+    for version in ${_py3_versions[@]}; do
+        echo "Installing/updating Python $version"
+        pyenv install --skip-existing $version
+        pyenv rehash  # needed on a first install
+
+        # Start the new environment with the latest pip and setuptools versions
+        PYENV_VERSION=$version pip install --upgrade pip setuptools
+        PYENV_VERSION=$version python -c "import sys; print(sys.version)"
+
+        # Put the specified utilities in the fresh environments or update them
+        for lib in ${_py3_site_packages[@]}; do
+            PYENV_VERSION=$version pip install --upgrade $lib
+        done
+    done
+
+    # Create a virtualenv based off the latest Python version to host global utilities
+    echo "Installing/updating the global Python utilities"
+    pyenv virtualenv $_py3_versions[1] 'utils'
+    pyenv rehash  # needed on a first install
+    PYENV_VERSION='utils' pip install --upgrade pip setuptools
+    for util in ${_py3_utils[@]}; do
+        PYENV_VERSION='utils' pip install --upgrade $util
+    done
+
+    # Create a virtualenv based off the latest Python version for interactive usage
+    echo "Installing/updating the default/interactive Python environment"
+    pyenv virtualenv $_py3_versions[1] 'interactive'
+    pyenv rehash  # needed on a first install
+    PYENV_VERSION='interactive' pip install --upgrade pip setuptools
+    # Install some tools to make interactive usage nicer
+    PYENV_VERSION='interactive' pip install --upgrade black bpython ipython
+
+    # Put all Python binaries/virtualenvs and the utilities on the $PATH
+    pyenv global 'interactive' $_py3_versions 'utils' $_py2_version
+}
+
+
+
 # =============================
 # Automate the update machinery
 # =============================
@@ -280,6 +387,21 @@ _update_zplug() {
 }
 
 
+_update_python() {
+    echo 'Updating the Python tool chain'
+
+    if _command_exists pyenv; then
+        pyenv update
+        create-or-update-python-envs
+    fi
+
+    if _command_exists zsh-pip-cache-packages; then
+        zsh-pip-clear-cache
+        zsh-pip-cache-packages
+    fi
+}
+
+
 run-private-scripts() {  # in the Nextcloud
     if [ -d "$HOME/data/getraenkemarkt/shell" ]; then
         for file in $HOME/data/getraenkemarkt/shell/*.sh; do
@@ -298,6 +420,7 @@ update-machine() {
     _command_exists snap && sudo snap refresh && _remove_old_snaps
     _update_repositories
     _update_zsh
+    _update_python
 
     sudo --reset-timestamp
 }