pyenv initialization update

- pyenv init optional
- check pyenv command before populate PATH
- always load user site packages directory

modules/python/README.md

@@ -26,6 +26,10 @@ Local Python Installation
 [pyenv][4] builds and installs multiple Python versions locally in the home
 directory.
 
+```sh
+zstyle ':prezto:module:python:pyenv' auto-init 'yes'
+```
+
 This module prepends the pyenv directory to the path variable to enable the
 execution of `pyenv`.
 

modules/python/init.zsh

@@ -7,21 +7,24 @@
 #   Patrick Bos <egpbos@gmail.com>
 #
 
+if zstyle -t ':prezto:module:python:pyenv' auto-init 'yes'; then
   # Load manually installed pyenv into the shell session.
-if [[ -s "$HOME/.pyenv/bin/pyenv" ]]; then
+  if [[ -s "$HOME/.pyenv/bin/pyenv" ]] && (( ! $+commands[pyenv] )); then
     path=("$HOME/.pyenv/bin" $path)
     export PYENV_ROOT=$(pyenv root)
-  eval "$(pyenv init - --no-rehash zsh)"
+  fi
 
-# Load package manager installed pyenv into the shell session.
-elif (( $+commands[pyenv] )); then
-  export PYENV_ROOT=$(pyenv root)
+  # Return if requirements are not found.
+  if (( ! $+commands[python] && ! $+commands[pyenv] )); then
+    return 1
+  elif (( $+commands[python] )); then
+    if (( $+commands[pyenv] )) && [[ -z "$PYENV_SHELL" ]]; then
       eval "$(pyenv init - --no-rehash zsh)"
+    fi
 
     # Prepend PEP 370 per user site packages directory, which defaults to
     # ~/Library/Python on macOS and ~/.local elsewhere, to PATH. The
     # path can be overridden using PYTHONUSERBASE.
-else
     if [[ -n "$PYTHONUSERBASE" ]]; then
       path=($PYTHONUSERBASE/bin $path)
     elif [[ "$OSTYPE" == darwin* ]]; then
@@ -31,10 +34,6 @@ else
       path=($HOME/.local/bin $path)
     fi
   fi
-
-# Return if requirements are not found.
-if (( ! $+commands[python] && ! $+commands[pyenv] )); then
-  return 1
 fi
 
 function _python-workon-cwd {