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Your Development Environment

Text Editors

Just about anything which can edit plain text will work for writing Python code, however, using a more powerful editor may make your life a bit easier.

VIM

Vim is a text editor which uses keyboard shortcuts for editing instead of menus or icons. There exist a couple of plugins and settings for the VIM editor to aid python development. If you only develop in Python, a good start is to set the default settings for indentation and linewrapping to values compliant with PEP 8. In your home directory, open a file called .vimrc and add the following lines:

set textwidth=79
set shiftwidth=4
set tabstop=4
set expandtab
set softtabstop=4
set shiftround

With these settings, newlines are inserted after 79 characters and indentation is set to 4 spaces per tab. If you also use VIM for other languages, there is a handy plugin at indent, which handles indentation settings for python source files.

There is also a handy syntax plugin at syntax featuring some improvements over the syntax file included in VIM 6.1.

These plugins supply you with a basic environment for developing in Python. To get the most out of Vim, you should continually check your code for syntax errors and PEP8 compliance. Luckily PEP8 and Pyflakes will do this for you. If your VIM is compiled with +python you can also utilize some very handy plugins to do these checks from within the editor.

For PEP8 checking, install the vim-pep8 plugin, and for pyflakes you can install vim-pyflakes. Now you can map the functions Pep8() or Pyflakes() to any hotkey or action you want in Vim. Both plugins will display errors at the bottom of the screen, and provide an easy way to jump to the corresponding line. It's very handy to call these functions whenever you save a file. In order to do this, add the following lines to your vimrc:

autocmd BufWritePost *.py call Pyflakes()
autocmd BufWritePost *.py call Pep8()

.. todo:: add supertab notes

TextMate

"TextMate brings Apple's approach to operating systems into the world of text editors. By bridging UNIX underpinnings and GUI, TextMate cherry-picks the best of both worlds to the benefit of expert scripters and novice users alike."

Sublime Text

"Sublime Text is a sophisticated text editor for code, html and prose. You'll love the slick user interface and extraordinary features."

Sublime Text has excellent support for editing Python code and uses Python for its plugin API.

Sublime Text 2 is currently in beta.

IDEs

PyCharm / IntelliJ IDEA

PyCharm is developed by JetBrains, also known for IntelliJ IDEA. Both share the same code base and most of PyCharm's features can be brought to IntelliJ with the free Python Plug-In.

Eclipse

The most popular Eclipse plugin for Python development is Aptana's PyDev.

Komodo IDE

Komodo IDE is developed by ActiveState and is a commercial IDE for Windows, Mac and Linux.

Spyder

Spyder an IDE specifically geared toward working with scientific python libraries (namely Scipy). Includes integration with pyflakes, pylint, and rope.

Spyder is open-source (free), offers code completion, syntax highlighting, class and function browser, and object inspection.

WingIDE

WingIDE a python specific IDE. Runs for Linux, Windows, and Mac (as an X11 application, which frustrates some Mac users).

Interpreter Tools

virtualenv

Virtualenv is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them. It solves the "Project X depends on version 1.x but, Project Y needs 4.x" dilemma and keeps your global site-packages directory clean and manageable.

virtualenv creates a folder which contains all the necessary executables to contain the packages that a Python project would need. An example workflow is given.

Install virtualenv:

$ pip install virtualenv

Create a virtual environment for a project:

$ cd my_project
$ virtualenv venv

virtualenv venv will create a folder in the currect directory which will contain the Python executable files, and a copy of the pip library which you can use to install other packages. The name of the virtual environment (in this case, it was venv) can be anything; omitting the name will place the files in the current directory instead.

In order the start using the virtual environment, run:

$ source venv/bin/activate

The name of the current virtual environment will now appear on the left of the prompt (e.g. (venv)Your-Computer:your_project UserName$) to let you know that it's active. From now on, any package that you install using pip will be placed in the venv folder, isolated from the global Python installation. Install packages as usual:

$ pip install requests

To stop using an environment simply type deactivate. To remove the environment, just remove the directory it was installed into. (In this case, it would be rm -rf venv).

Other Notes

Running virtualenv with the option --no-site-packages will not include the packages that are installed globally. This can be useful for keeping the package list clean in case it needs to be accessed later.

In order to keep your environment consistent, it's a good idea to "freeze" the current state of the environment packages. To do this, run

$ pip freeze > requirements.txt

This will create a requirements.txt file, which contains a simple list of all the packages in the current environment, and their respective versions. Later, when a different developer (or you, if you need to re- create the environment) can install the same packages, with the same versions by running

$ pip install -r requirements.txt

This can help ensure consistency across installations, across deployments, and across developers.

Lastly, remember to exclude the virtual environment folder from source control by adding it to the ignore list.

virtualenvwrapper

Virtualenvwrapper makes virtualenv a pleasure to use by wrapping the command line API with a nicer CLI.

$ pip install virtualenvwrapper

Put this into your ~/.bash_profile (Linux/Mac) file:

$ export VIRTUALENVWRAPPER_VIRTUALENV_ARGS='--no-site-packages'

This will prevent your virtualenvs from relying on your (global) site packages directory, so that they are completely separate..

Other Tools

IPython

IPython provides a rich toolkit to help you make the most out of using Python interactively. Its main components are:

  • Powerful Python shells (terminal- and Qt-based).
  • A web-based notebook with the same core features but support for rich media, text, code, mathematical expressions and inline plots.
  • Support for interactive data visualization and use of GUI toolkits.
  • Flexible, embeddable interpreters to load into your own projects.
  • Tools for high level and interactive parallel computing.
$ pip install ipython

BPython

bpython is an alternative interface to the Python interpreter for Unix-like operating systems. It has the following features:

  • In-line syntax highlighting.
  • Readline-like autocomplete with suggestions displayed as you type.
  • Expected parameter list for any Python function.
  • "Rewind" function to pop the last line of code from memory and re-evaluate.
  • Send entered code off to a pastebin.
  • Save entered code to a file.
  • Auto-indentation.
  • Python 3 support.
$ pip install bpython