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Posts Tagged ‘python’

Python Development on Linux and Why You Should Too

September 1st, 2012 25 comments

If you’re a programmer and you use Linux but you haven’t yet entered the amazing world that is Python development, you’re really missing out on something special. For years, I dismissed Python as just another script kiddie language, eschewing it for more “serious” languages like Java and C#. What I was missing out on were the heady days of rapid development that I so enjoyed while hacking away on Visual Basic .NET in my early years of university.

There was a time when nary a day would go by without me slinging together some code into a crappy Windows Forms application that I wrote to play with a new idea or to automate an annoying task. By and large, these small projects ceased when I moved over to Linux, partially out of laziness, and partially because I missed the rapid prototyping environment that Visual Basic .NET provided. Let’s face it – Java and C# are great languages, but getting a basic forms app set up in either of them takes a significant amount of time and effort.

Enter Python, git/github, pip, and virtualenv. This basic tool chain has got me writing code in my spare time again, and the feeling is great. So without further ado, let me present (yet another) quick tutorial on how to set up a bad-ass Python development environment of your own:

Step 1: Python

If there’s one thing that I really love about Python, it’s the wide availability of libraries for most any task that one can imagine. An important part of the rapid prototyping frame of mind is to not get bogged down on writing low-level libraries. If you have to spend an hour or two writing a custom database interface layer, you’re going to lose the drive that got you started in on the project in the first place. Unless of course, the purpose of the project was to re-invent the database interface layer. In that case, all power to you. In my experience, this is never a problem with Python, as its magical import statement will unlock a world of possibilities that is occupied by literally thousands of libraries to do most anything that you can imagine.

Install this bad boy with the simple command sudo apt-get install python and then find yourself a good python tutorial with which to learn the basics. Alternatively, you can just start hacking away and use StackOverflow to fill in any of the gaps in your knowledge.

Step 2: Git/Github

In my professional life, I live and die by source control. It’s an excellent way to keep track of the status of your project, try out new features or ideas without jeopardizing the bits of your application that already work, and perhaps most importantly, it’s a life saver when you can’t figure out why in the hell you decided to do something that seemed like a good idea at the time but now seems like a truly retarded move. If you work with other developers, it’s also a great way to find out who to blame when the build is broken.

So why Git? Well, if time is on your side, go watch this 1 hour presentation by Linus Torvalds; I guarantee that if you know the first thing about source control, he will convince you to switch. If you don’t have that kind of time on your hands (and really, who does?) suffice it to say that Git plays really well with Github, and Github is like programming + social media + crack. Basically, it’s a website that stores your public (or private) repositories, showing off your code for all the world to see and fork and hack on top of. It also allows you to find and follow other interesting projects and libraries, and to receive updates when they make a change that you might be interested in.

Need a library to do fuzzy string matching? Search Git and find fuzzywuzzy. Install it into your working environment, and start playing with it. If it doesn’t do quite what you need, fork it, check out the source, and start hacking on it until it does! Github is an amazing way to expand your ability to rapid prototype and explore ideas that would take way too long to implement from scratch.

Get started by installing git with the command sudo apt-get install git-core. You should probably also skim through the git tutorial, as it will help you start off on the right foot.

Next, mosey on over to Github and sign up for an account. Seriously, it’s awesome, stop procrastinating and do it.

Step 3: Pip

I’ve already raved about the third-party libraries for Python, but what I haven’t told you yet is that there’s an insanely easy way to get those libraries into your working environment. Pip is like a repository just for Python libraries. If you’re already familiar with Linux, then you know what I’m talking about. Remember the earlier example of needing a fuzzy string matching library in your project? Well with pip, getting one is as easy as typing pip install fuzzywuzzy. This will install the fuzzywuzzy library on your system, and make it available to your application in one easy step.

But I’m getting ahead of myself here: You need to install pip before you can start using it. For that, you’ll need to run sudo apt-get install python-setuptools python-dev build-essential && sudo easy_install -U pip

The other cool thing about pip? When you’re ready to share your project with others (or just want to set up a development environment on another machine that has all of the necessary prerequisites to run it) you can run the command pip freeze > requirements.txt to create a file that describes all of the libraries that are necessary for your app to run correctly. In order to use that list, just run pip install -r requirements.txt on the target machine, and pip will automatically fetch all of your projects prerequisites. I swear, it’s fucking magical.

Step 4: Virtualenv

As I’ve already mentioned, one of my favourite things about Python is the availability of third-party libraries that enable your code to do just about anything with simple import statement. One of the problems with Python is that trying to keep all of the dependencies for all of your projects straight can be a real pain in the ass. Enter virtualenv.

This is an application that allows you to create virtual working environments, complete with their own Python versions and libraries. You can start a new project, use pip to install a whole bunch of libraries, then switch over to another project and work with a whole bunch of other libraries, all without different versions of the same library ever interfering with one another. This technique also keeps the pip requirements files that I mentioned above nice and clean so that each of your projects can state the exact dependency set that it needs to run without introducing cruft into your development environment.

Another tool that I’d like to introduce you to at this time is virtualenvwrapper. Just like the name says, it’s a wrapper for virtualenv that allows you to easily manage the many virtual environments that you will soon have floating around your machine.

Install both with the command pip install virtualenv virtualenvwrapper

Once the installation has completed, you’ll may need to modify your .bashrc profile to initialize virtualenvwrapper whenever you log into your user account. To do so, open up the .bashrc file in your home directory using your favourite text editor, or execute the following command: sudo nano ~/.bashrc 

Now paste the following chunk of code into the bottom of that file, save it, and exit:

# initialize virtualenv wrapper if present
if [ -f /usr/local/bin/virtualenvwrapper.sh ] ; then
. /usr/local/bin/virtualenvwrapper.sh
fi

Please note that this step didn’t seem to be necessary on Ubuntu 12.04, so it may only be essential for those running older versions of the operating system. I would suggest trying to use virtualenvwrapper with the instructions below before bothering to modify the .bashrc file.

Now you can make a new virtual environment with the command mkvirtualenv <project name>, and activate it with the command workon <project name>. When you create a new virtual environment, it’s like wiping your Python slate clean. Use pip to add some libraries to your virtual environment, write some code, and when you’re done, use the deactivate command to go back to your main system. Don’t forget to use pip freeze inside of your virtual environment to obtain a list of all of the packages that your application depends on.

Step 5: Starting a New Project

Ok, so how do we actually use all of the tools that I’ve raved about here? Follow the steps below to start your very own Python project:

  1. Decide on a name for your project. This is likely the hardest part. It probably shouldn’t have spaces in it, because Linux really doesn’t like spaces.
  2. Create a virtual environment for your project with the command mkvirtualenv <project name>
  3. Activate the virtual environment for your project with the command workon <project name>
  4. Sign into Github and click on the New Repository button in the lower right hand corner of the home page
  5. Give your new repository the same name as your project. If you were a creative and individual snowflake, the name won’t already be taken. If not, consider starting back at step 1, or just tacking your birth year onto the end of the bastard like we used to do with hotmail addresses back in the day.
  6. On the new repository page, make sure that you check the box that says Initialize this repository with a README and that you select Python from the Add .gitignore drop down box. The latter step will make sure that git ignores files types that need not be checked into your repository when you commit your code.
  7. Click theCreate Repository button
  8. Back on your local machine, Clone your repository with the command git clone https://github.com/<github user name>/<project name> this will create a directory for your project that you can do all of your work in.
  9. Write some amazing fucking code that blows everybody’s minds. If you need some libraries (and really, who doesn’t?) make sure to use the pip install <library name> command.
  10. Commit early, commit often with the git commit -am “your commit message goes here” command
  11. When you’re ready to make your work public, post it to github with the command git push https://github.com/<github user name>/<project name>
  12. Don’t forget to script out your project dependencies with the pip freeze > requirements.txt command
  13. Finally, when you’re finished working for the day, use the deactivate command to return to your normal working environment.

In Conclusion:

This post is way longer than I had originally intended. Suck it. I hope your eyes are sore. I also hope that by now, you’ve been convinced of how awesome a Python development environment can be. So get out there and write some amazing code. Oh, and don’t forget to check out my projects on github.




On my Laptop, I am running Linux Mint 12.
On my home media server, I am running Ubuntu 12.04
Check out my profile for more information.
Categories: Jon F, Programming Tags: , ,

Eclipse Fails It

September 14th, 2009 No comments

Man, Eclipse works great on Debian! It gives me this cool message on startup:

JVM terminated. Exit code=127
/usr/lib/jvm/java-gcj/bin/java
-Djava.library.path=/usr/lib/jni
-Dgnu.gcj.precompiled.db.path=/var/lib/gcj-4.2/classmap.db
-Dgnu.gcj.runtime.VMClassLoader.library_control=never
-Dosgi.locking=none
-jar /usr/lib/eclipse/startup.jar
-os linux
-ws gtk
-arch x86
-launcher /usr/lib/eclipse/eclipse
-name Eclipse
-showsplash 600
-exitdata 3a0015
-install /usr/lib/eclipse
-vm /usr/lib/jvm/java-gcj/bin/java
-vmargs
-Djava.library.path=/usr/lib/jni
-Dgnu.gcj.precompiled.db.path=/var/lib/gcj-4.2/classmap.db
-Dgnu.gcj.runtime.VMClassLoader.library_control=never
-Dosgi.locking=none
-jar /usr/lib/eclipse/startup.jar

After uninstalling, reinstalling, changing which JVM I was using, uninstalling, reinstalling, googling, yahooing, and binging, I finally found this post over at Debian Help that instructed me to first install XULRunner. With the addition of this simple step, everything suddenly worked great.

The strange part about the whole thing is that Eclipse doesn’t install XULRunner as a dependency, and the Wikipedia article about XULRunner doesn’t mention Eclipse anywhere. I don’t really understand their relationship, aside from the fact that Eclipse supports plugins that may or may not be written on top of XULRunner.

Regardless of their strange and undocumented relationship, the Eclipse/XULRunner combo seem to work perfectly, allowing me to create Java, C/C++, and Plugin projects out of the box. Next steps include adding plugins for Subversion, Python, and PHP.