This document contains a description on setting up a Python developer environment on OS X. This document has been tested on OS X 10.9.5. If you find errors or if you find anything missing, please send in a pull request with your changes. All pull requests are well accepted.
There are many great tools that can help you writing awesome Python code. The tools that are mentioned in this documents are the ones I use daily when working with Python code.
If you have used other Unix-like operating systems, such as Linux or BSD, you must have used some kind of package manager for installing software. If you have used OS X for some time you might have noticed that such functionality is completely missing. There are several projects out there which solve this problem. My favorite one, that I trust and love is Homebrew. They even use the subtitle "The missing package manager for OS X".
To install Homebrew you first need to install Xcode and the Xcode command line tools. The Xcode command line tool contains various of Unix tools which Brew depend on, such as Git.
If you don't have Xcode you must start by installing it. It might take a while, since Xcode is a big application (2.46 GB last time i checked). To install Xcode, open up the App Store application that comes with OS X, search for Xcode and click the Free button.
When Xcode is installed, you need to open it and accept a million line licence term before you can use the Xcode command line tools. Open up a terminal and type in
sudo git
Type in your password, and agree to the licence terms. After that commands like
git and gcc should be available in your terminal.
Next we install Homebrew. Open up a terminal and type in the following.
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
If you are the kind of person that is not willing to run scripts without reading them, well in this case it should be safe. I trust the Homebrew guys. If not, read through the scripts before you execute them in your shell.
When the install finishes, run
brew doctor
If everything worked as planned you should get a message from Brew doctor stating that your system is ready to brew. If not, Brew doctor will tell you what went wrong and try to help you fix it.
We know use Brew to install Python and other Python utilities.
Python 2.7 is installed by default on OS X but the Python shared library and the library headers are missing. Many python packages which are not written in Python depend on these things.
To install Python and with shared objects and header files, open up your terminal and ask Brew to install it for us.
brew install python --framework
If you do brew list you can see all packages (most often referred to as
formulae in brew) that have been installed with Brew.
Pip is a package management system used to install and manage software packages written in Python. Many packages can be found in the Python Package Index PyPI but packages can be installed directly from Github or from local packages on your machine.
With Pip we can install external Python packages that we need in our Python projects. To name a few, these can be Flask, Django or SQLAlchemy.
When we installed Python using Brew in the section above we installed Pip as well. We use Pip heavily when we are writing our Python projects in this course so be sure to install it properly.
Next we install Python virtualenv. This one is my favourite and I can't understand how I was able to live without it couple of years ago. Virtualenv allows you to create a virtual environment, put simply, an isolated working copy of Python which allows you to work on a specific project without worry of affecting other projects. For example, if you are working on two different projects with different dependencies you can install them into the virtualenv without installing it into the global Python installation on your machine. Brilliant. When the virtualenv is active you can use all the packages that were installed into that environment. When you are done, you remove the environment without leaving any trace of files on your hard drive.
To install virtualenv, open up your terminal and type in the following.
sudo pip install virtualenv
Before you continue, take a brew moment and Google Pip and virtualenv and read more about them. They will make your life so much easier in the future. I recommend this blog post by Jamie Matthews to start with.
Now let's take our new environment for a spin and write a small application that prints out to the stdout the movies that are being shown in the Icelandic theatres. We use the apis.is/cinema API. Be sure to give them some follow up on their Github page. Great API that you can use in your applications.
Our application will depend on two Python packages:
Create a folder somewhere on your disk, I used ~/Desktop/movies. You can do the same.
➜ mkdir ~/Desktop/cinema
➜ cd ~/Desktop/cinema
In that folder we will create a Python virtualenv (under the folder .venv) for the external packages that we depend on.
➜ cinema virtualenv .venv
New python executable in .venv/bin/python2.7
Also creating executable in .venv/bin/python
Installing setuptools, pip...done.
Next we enable the virtualenv in our shell. Note that you are only activating the virtualenv in the shell that you are using. If you open up a new one you must enable the virtualenv for that shell as well.
➜ cinema source .venv/bin/activate
(.venv)➜ cinema
Next we install the two above mentioned packages into our virtualenv. Pip
packages can be install with pip install. You can also search on Pypi using
pip search.
(.venv)➜ cinema pip install requests
Downloading/unpacking requests
Downloading requests-2.4.1-py2.py3-none-any.whl (458kB): 458kB downloaded
Installing collected packages: requests
Successfully installed requests
Cleaning up...
(.venv)➜ cinema pip install termcolor
Downloading/unpacking termcolor
Downloading termcolor-1.1.0.tar.gz
Running setup.py (path:/Users/hlysig/Desktop/cinema/.venv/build/termcolor/setup.py) egg_info for package termcolor
Installing collected packages: termcolor
Running setup.py install for termcolor
Successfully installed termcolor
Cleaning up...
Now open up your favourite text editor and type (or paste) the following code into file named cinema.py:
import json
import sys
import requests
from termcolor import colored
def show_running_movies():
"""
Fetches movies that are beeing shown in Icelandic theaters and
prints them out to stdout
"""
# Do a get request to cinema api at apis.is
response = requests.get('http://apis.is/cinema')
# If we don't receive a 2xx status code, we stop and print error.
if not response.ok:
print 'Unable to read from api, got non ok status code: {0}'\
.format(response.status_code)
sys.exit(1)
# The response is on json format. We use python json module to
# parse the json
# and map it into a Python associated array (dictionary)
d = json.loads(response.text)
# We loop through the result and print it to stdout.
for res in d.get('results'):
print colored(res.get('title').encode('utf-8'), 'yellow')
for showtime in res.get('showtimes'):
print ' ', showtime.get('theater').encode('utf-8')
for schedule in showtime.get('schedule'):
print ' ', schedule.encode('utf-8')
if __name__ == '__main__':
show_running_movies()
Exit your editor and run the script.
(.venv)➜ cinema python cinema.py
Afinn
Sambíóin Álfabakka
15:20 (1)
15:20 (P)
17:40 (1)
...
If everything went well the script should print out the movies that are being shown. Nice, ey?
If you are new to Python please stop and read through the code and convince yourself that it does what it is meant to do. The author of the Python language states that the language is so simple that it is almost identical to natural languages. I don't agree. But simple well written Python code can be that way; and most often in large Python code base things can be quite tricky. But that is my rant. Don't take my word for it.
You should now have everything setup for writing Python code on your Mac.