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Tidy up virtual_environment.rst
Some small fixes.
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‎virtual_environment.rst‎

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Virtual Environment
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-------------------
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Have you ever heard of ``virtualenv``? The chances are that if you are a
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beginner then you might not have heard about it but if you are a
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seasoned programmer than it's a vital part of your toolset. So what
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``virtualenv`` really is? ``Virtualenv`` is a tool which allows us to
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Have you ever heard of ``virtualenv``? If you are a beginner,
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then you might not have heard about it but if you are a
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seasoned programmer then it may well be a vital part of your toolset.
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So what is ``virtualenv``? ``Virtualenv`` is a tool which allows us to
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make isolated python environments. Imagine you have an application that
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needs version 2 of a LibraryBar, but another application requires
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needs version 2 of a library, but another application requires
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version 3. How can you use and develop both these applications?
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If you install everything into ``/usr/lib/python2.7/site-packages`` (or
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whatever your platform's standard location is), it's easy to end up in a
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situation where you unintentionally upgrade a package that shouldn't be
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upgraded. In another case just imagine that you have an application
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which is fully developed and you do not want to make any change to the
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libraries it is using but at the same time you start developing another
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application which requires the updated versions of those libraries. What
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will you do? It is where ``virtualenv`` comes into play. It creates
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isolated environments for your python application and allows you to
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install Python libraries in that isolated environment instead of
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installing them globally.
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In order to install it just type this command in the shell:
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situation where you unintentionally upgrade a package.
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In another case, imagine that you have an application which is fully
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developed and you do not want to make any change to the libraries it is
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using but at the same time you start developing another application
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which requires the updated versions of those libraries.
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What will you do? Use ``virtualenv``! It creates isolated environments
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for your python application and allows you to install Python libraries
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in that isolated environment instead of installing them globally.
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To install it, just type this command in the shell:
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.. code:: python
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$ pip install virtualenv
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Now i am going to list some of it's commands. The most important ones
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are:
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The most important commands are:
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- ``$ virtualenv myproject``
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- ``$ source bin/activate``
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This first one makes an isolated virtualenv environment in the
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``myproject`` folder and the second command activates that isolated
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environment. While running the first command you have to make a
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decision.
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environment.
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While creating the virtualenv you have to make a decision. Do you
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want this virtualenv to use packages from your system ``site-packages``
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or install them in the virtualenv’s site-packages? By default,
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virtualenv will not give access to the global ``site-packages``.
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Do you want this virtualenv to use packages from your system
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``site-packages`` or install them in the virtualenv’s site-packages? By
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default, virtualenv will not give access to the global ``site-packages``.
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If you want your ``virtualenv`` to have access to your systems
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``site-packages`` use the ``--system-site-packages`` switch when creating
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``site-packages``, use the ``--system-site-packages`` switch when creating
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your virtualenv like this:
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.. code:: python
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$ deactivate
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Running `python` after deactivating will use your system installation
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of Python again.
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**Bonus**
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You can use ``smartcd`` which is a library for bash and zsh and allows
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directories. I have used it quite a lot and love it. You can read more
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about it on `GitHub <https://github.com/cxreg/smartcd>`__
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This was just a short intro to virtualenv. There's a lot more to it. For
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further study i recommend `this
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link. <http://docs.python-guide.org/en/latest/dev/virtualenvs/>`__
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It will remove all of your confusions about virtualenv.
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This was just a short intro to virtualenv. There's a lot more to it; `this
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link <http://docs.python-guide.org/en/latest/dev/virtualenvs/>`__ has more
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information.

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