Added virtual environment enforcing for pip for the osx installation tutorial

Can Ibanoglu · Can Ibanoglu · commit d17acbf5151c · 2013-11-08T21:21:56.000+02:00
diff --git a/docs/starting/install/osx.rst b/docs/starting/install/osx.rst
@@ -119,6 +119,49 @@ An useful set of extensions to virtualenv is available in virtualenvwrapper,
 `RTFD <http://virtualenvwrapper.readthedocs.org/en/latest/>`_ to find out more.
 
 
+A note about Pip and Virtualenv
+-------------------------------
+
+By now it should be clear that using virtual environments is a great way to keep
+your development environment clean and keeping different projects' requirements
+separate. 
+
+When you start working on many different projects, it can be hard to remember to
+activate the related virtual environment when you come back to a specific project.
+As a result of this, it is very easy to install packages globally while thinking
+that you are actually installing the package for the virtual environment of the
+project. Over time this can result in a messy global package list.
+
+In order to make sure that you install packages to your active virtual environment
+when you use ``pip install``, consider adding the following two lines to your
+``~/.bashrc`` file:
+
+.. code-block:: console
+    export PIP_REQUIRE_VIRTUALENV=true
+
+After saving this change and sourcing the ``~/.bashrc`` file with ``source ~/.bashrc``,
+pip will no longer let you install packages if you are not in a virtual environment.
+If you try to use ``pip install`` outside of a virtual environment pip will
+gently remind you that an activated virtual environment is needed to install
+packages.
+
+.. code-block:: console
+    $ pip install requests
+    Could not find an activated virtualenv (required).
+
+You will of course need to install some packages globally and this can be accomplished
+by adding the following to your ``~/.bashrc`` file:
+
+.. code-block:: console
+    gpip() {
+        PIP_REQUIRE_VIRTUALENV="" pip "$@"
+    }
+
+After saving the changes and sourcing your ``~/.bashrc`` file you can now install
+packages globally by running ``gpip install``. You can change the name of the 
+function to anything you like, just keep in mind that you will have to use that 
+name when trying install packages globally with pip.
+
 --------------------------------
 
 This page is a remixed version of `another guide <http://www.stuartellis.eu/articles/python-development-windows/>`_,
