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Often you need to change or extend Eclipse functionality. This guide try to help getting into the Eclipse source code.

In additional to this developers are frequently advised to read existing high-quality code. Having easy access to the Eclipse sources can be extremely helpful in familiarizing yourself with the coding patterns inherent in Eclipse

Eclipse is a powerful, extensible IDE for building general purpose applications. Some of the key player in creating Eclipse are also well known for their software architecture skills. So you can learn a lot from the Eclipse code base.

The Eclipse code base can be imported directly from your installed Eclipse version or can be access via the cvs or svn version control system. The article describes both approaches.

The following describes how you can import Eclipse plugins from your Eclipse installation to review the code.

Select File -> Import. Select "Plug-ins and Fragments".

Make the following settings.

Add all plugins you would like to import and press "Finish". In my example I import only "org.eclipse.ui.intro".

You can you investigate the code of the imported plugins.

Eclipse allows to trace a running Eclipse and to write information to the console. This can be used to identify which command is associated with a certain keybinding.

To use this create a runtime configuration which contains the Eclipse plugins you are interested in, e.g. include "org.eclipse.ui" and press add required plugins.

In the "Run Configuration" switch to the "Tracing" tab and set "Enable Tracing". Select the "org.eclipse.ui" plugin. Flag "debug".

Scroll down and select "trace/keybindings" and "trace/keybindings.verbose".

Make sure you have the -consoleLog flag maintained as an argument.

If you start now the Eclipse IDE then everytime you use a shortcut the calling Eclipse will display a trace which contains the commandId.

In your calling Eclipse you can now use Search (text) to find the handler / action which implements this command.

You can also debug the Eclipse IDE if you want to see how certain things are done. Use for example the Plugin Spy to find the class / plugin which you would like to invest. Put a breakpoint into the coding, for example in the constructor of the class or if the class shows UI elements "createPartControl". Create a Run Configuration which includes all Eclipse IDE plugins and run it.

If you now select Run -> Debug for your runtime configuration you can start debugging the interesting point.

Eclipse projects can use cvs and svn as version control system. The majority of the project still uses cvs. Downloading the source code from a version control system is called "checkout".

7.1. CVS

To access the Eclipse CVS repositories open the "CVS Repositories" view via Window -> Show View -> Other -> CVS -> CVS Repositories

Create a repository by right clicking in the view and selecting "New" -> "Repository Location".

Copy the following string and paste it into the CVS view to create a new repository.

				
:pserver:anonymous@dev.eclipse.org:/cvsroot/eclipse
			

You can check the created properties via right-mouse click on the entry -> Properties

Now can you browse the structure and check out code. Check out will create a local copy of the selected path into your workspace.

Not all Eclipse projects are in the same path. For example here are some connection strings.

Table 1. Access to some

Project	Description
Eclipse Main	:pserver:anonymous@dev.eclipse.org:/cvsroot/eclipse
Eclipse PDE CVS repository	:pserver:anonymous@dev.eclipse.org:/cvsroot/eclipse then find the folder pde
Eclipse Equinox CVS repository	:pserver:anonymous@dev.eclipse.org:/cvsroot/rt

More information about cvs access can be found Eclipse cvs access

Tip

You can browse the CVS source code in the CVS online repository

Tip

Eclipse projects often provide "Project Set Files" (.psf) which allow to checkout a logical connected set of plugins directly from cvs. Via these files you can easily get a consistent working copy of a set of plugins. See Eclipse PSF Wiki for details and see Eclipse PDE contributor Guide for an example.

7.3. git

Eclipse mirrors the cvs repositories into Git.

The Eclipse code is currently mainly maintained in cvs but this source code is mirrored into Git repositories.

Tip

You find the Git url for all projects at http://dev.eclipse.org/git/

Tip

Please note that the checkout via HTTP uses a different URL. You can switch to the HTTP urls on the webpage.

Please see Git with Eclipse EGit - Tutorial for details on how to use the EGit plugin.

All known Eclipse bugs and feature requests are stored in a Bugzilla database Eclipse Bugs

The following explains how you could use Mylyn to work on Bugs and store your content in the bugreport.

Mylyn is a task management system and allows to store the context (source files) in a task. This way you can work on a certain task, switch to another tasks and return to the same tasks and all the files you worked on are re-opened. See the Mylyn Tutorial for installation and basic usage.

Mylyn has build in support for the Eclipse bug database. Just right click in the "Task List" view and select New -> Query

Select "Eclipse" and press Next. Select "Create query" and if you know the bug already "Create query using form".

Lets assume you want to see all bugs for Eclipse 3.6 in PDE - UI then you could maintain the following query.

If you now activate a task you can use Mylyn to work on Eclipse bugs.

Thank you for practicing with this tutorial.

For questions and discussion around this article please use the www.vogella.de Google Group. Also if you note an error in this article please post the error and if possible the correction to the Group.

I believe the following is a very good guideline for asking questions in general and also for the Google group How To Ask Questions The Smart Way.