MAC_Hints.rst: Add instructions for venv and pyenv

Commit adds instruction for venv and pyenv.

Closes coala/coala#3461

Author: rhemon

Help/MAC_Hints.rst

@@ -1,31 +1,42 @@
 Coverage Installation Hints for macOS Users:
 ============================================
 
+venv
+----
+
+Here we will be using ``venv``, which is part of python's standard
+libary since python 3.3, to create a virtualenv for development.
+
 1. Make sure you have installed Xcode and Homebrew.
 ---------------------------------------------------
 
-2. Install Python3.
--------------------
+2. Install Python 3.
+--------------------
+
+For coala you will need to use Python 3, so you may
+simply use homebrew to install Python 3, or you could also
+`refer to the pyenv section <#pyenv>`__ to install Python 3 while you can also
+maintain other python versions.
 
 ::
 
-    $ brew search python  # This should display python3
+    $ brew search python  # This should display Python 3
     $ brew install python3
     $ python3 --version   # To check the installed version
 
-3. Create Virtual Environments with pyvenv
-------------------------------------------
+3. Create Virtual Environments with venv
+----------------------------------------
 
 ::
 
     # Create Virtual Env named myenv
-    $ pyvenv myenv
+    $ python3 -m venv myenv
 
     # This will create a folder named myenv in the
     # current directory. To activate this environment just type
     $ source myenv/bin/activate
 
-    # You can start Python3 by typing:
+    # You can start Python 3 by typing:
     $ python
 
 4. Virtualenvwrapper with Python 3:
@@ -47,10 +58,10 @@ Coverage Installation Hints for macOS Users:
     # Activate Changes
     $ source ~/.bash_profile
 
-    # Get Python3 path (python3_pth)
+    # Get Python 3 path (python3_pth)
     $ which python3
 
-    # Create a new virtual environment with Python3
+    # Create a new virtual environment with Python 3
     $ mkvirtualenv --python=python3_path myenv
 
 Finally!
@@ -60,3 +71,49 @@ Finally!
 
     # Install python-coverage3 by
     $ easy_install coverage
+
+pyenv
+-----
+
+Here we show how to use pyenv, which is simply a python installer
+that allows you to install multiple python versions and switch
+through them. After installation, you may also want to set up
+a virtual environment using :code:`venv` or :code:`virtualenv`.
+
+1. Install pyenv with homebrew
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    $ brew update
+    $ brew install pyenv
+
+2. Installing and using python with pyenv
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To install python you simply have to
+do this (you don't have to install all of them) :
+
+::
+
+    $ pyenv install 3.5.0
+    $ pyenv install 3.4.3
+    $ pyenv install 3.3.6
+    $ pyenv install 3.2.6
+    $ pyenv install 2.7.10
+    $ pyenv versions # lists the versions you have
+
+To use a particular version you simply have to do this :
+
+::
+
+    $ pyenv local 3.5.0
+
+To know more about the available pyenv commands, please
+read their `Command Reference
+<https://github.com/pyenv/pyenv/blob/master/COMMANDS.md>`__.
+
+
+Presently, while using pyenv, tests for version-file-read fail,
+if interested you can
+have a look `here <https://github.com/yyuu/pyenv/issues/623>`__.