Getting the code

The first thing you probably want to do in order to code in PyDev is getting its code.

Pre-requisites: Eclipse SDK 3.8.0, Git and Java 5.0 (note that other versions of those should work too but details may differ a bit)

Before getting the code, there's an important step you need to make: Change your java 'compiler compliance-level' to 5.0. To do this, go to window > preferences > Java > compiler and change that setting from 1.4 to 5.0.

Repository

Get the code with Git from https://github.com/fabioz/Pydev (ideally, fork it at github, create your own branch at the forked repository -- usually based in the development branch -- and later send a pull request on github so that the code can be merged back). Later, if you want to provide some other feature/bugfix, a new branch should be created again.

Then, in Eclipse, go to: File > Import > Existing projects into workspace and point it to the root of the repository you just downloaded.

Configuring the environment after getting the code

Important: Before doing any changes to the code it's important to note that you should create a new branch (usually based on the development branch) for doing code changes. See: http://book.git-scm.com/3_basic_branching_and_merging.html and also http://nvie.com/git-model for details on creating and using branches.

Note: for running the tests the file: org.python.pydev.core/tests/org.python.pydev.core/TestDependent.OS.properties must have the values set regarding to the computer that'll execute the tests.

Note that to make sure that PyDev keeps working on the long run, usually tests are required for pull requests (unless it's a really trivial change). Those reside in the project/tests source folder.

Note that if the head does not compile in git, send an e-mail to the pydev-code list at sourceforge to know what's happening.

Running it with your changes

After you download the contents and do changes to the code, you can do a Run As > Eclipse Application and a new Eclipse instance will be run with the changes you did.

Where to start?

Ok, this may be the most difficult thing... especially because answers may change a lot depending on what you want to do, so, below are outlined 2 different approaches:

Extending PyDev with Jython: recommended if you want to add some editor-related action or something that does not need implementing some Eclipse extension-point.
Extending PyDev in Java: if you want something that won't map to an action, this might be the better way to go.

To start in any of those approaches it might be worth taking a look at some Eclipse documentation, to try to grasp some of its concepts. One of the finest documentations for that is the Eclipse FAQ.

If you want to take the Jython approach, check out this article on how to do jython scripting in PyDev

For supporting a new Python based language, the first step would be creating a grammar that can parse it while providing a Python like AST. See: PyDev Grammar for instructions on that.

And that's it. If you have further doubts about how to code in PyDev, direct your questions to the pydev-code list at sourceforge.

Creating a distribution locally

Provided that the steps were followed, PyDev should have the following structure:

/builders /org.python.pydev.build

/features /org.python.pydev.feature

/plugins /org.python.pydev ... (other plugins)

Now, on to the build: start a shell and follow the instructions at /plugins/org.python.pydev.build/build_cmd.txt (read the end of the file for details on customizing it properly)

Contributing back

Create a pull request in github: http://help.github.com/send-pull-requests/