CDT/policy

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Code Formatting

  • It is recommended to use default "Eclipse" code formatting for Java for new code. Please don't rely on Java auto-formatter that is known to be buggy (see bug 303519).
  • It is recommended to preserve formatting of old code when making patches

Eclipse Java Errors/Warnings

It is strongly recommended for cdt plugins to override default compiler error/warning and use project specific errors/warnings. Projects should have the following customizations:

  • Method with a constructor name - Error
  • Assignment has no effect - Error
  • Possible accidental boolean assignment - Error
  • finally does not complete normally - Error
  • Using a char array in string concatenation - Error
  • Null pointer access - Error
  • Potential null pointer access - Warning
  • Unused Import - Error

All commiters and contributors submitting patches should enable API tooling by setting target baseline platform. Do not commit code with API errors.

Patches with errors listed above including API errors will not be accepted without corrections.

Committers who wish to keep a plugin warning-free should update the project as follows. These steps turns warnings into errors and leaves everything else in the ignore state. In other words, the idea is not to turn everything into an error, just the things that are set to generate a warning.

  1. Open project properties > Java Compiler > Errors/Warnings
    1. Turn on Enable project specific settings
    2. Turn on Annotations > Suppress optional errors with '@SuppressWarnings' (new pref in Helios)
  2. Open .setings/org.eclipse.jdt.core.prefs in a text editor and do a find&replace of "=warning" to "=error" (use Replace All)
  3. Turn on project properties > Plug-in Development > API Errors/Warnings > Use project settings
  4. Open .settings/org.eclipse.pde.api.tools.prefs in a text editor and do a find&replace of "=Warning" to "=Error" (use Replace All; 'W' and 'E' must be uppercase)
  5. Turn on project properties > Plug-in Development > Plug-in Manifest Compiler > Use project settings
  6. Open .settings/org.eclipse.pde.prefs in a text editor and do a find&replace of "=1" to "=0" (use Replace All)

Copyright

Use eclipse copyright header: http://www.eclipse.org/legal/copyrightandlicensenotice.php. Here is an example:

/*******************************************************************************
 * Copyright (c) 2008, 2010 XYZ Corp. and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Jane Doe (XYZ Corp.) - initial API and implementation
 *    John Smith (ABC Enterprises) - Multi-gadget support for the widget (bug 654321)
 *******************************************************************************/ 

Normally contributors line is added for significant changes in the file.

API

There are 3 types of API: Public API, Provisional API and Internal API (aka Private API, aka non API). Public API is what all client should use, it suppose to be documented (javadoc) and should not change much from version to version. If major version of the plugin changed it may contain API breakage. If minor version of the plugin changed it may contain API extensions (non-breaking changes). There is also some policies about changing API between milestone builds. Provisional API is a public API in making. It does not have to follow versioning and other rules of public API, but other than that, it can be threated as public.

Examples API breaking change:

  • Adding a method in interface
  • Changing method signature
  • Changing private visibility to any other

Examples of API extensions:

  • Adding new extension point
  • Changing visibility from protected to public
  • Adding method in a class

So here is what considered Internal API vs Public vs Provisional for CDT

  • Internal API
    • packages with name *.internal.*, *.examples.*
    • test projects, releng projects and feature projects
    • packages which are not exported or X-exported (i.e. not exported as public)
    • non-java code (i.e. native C code)
    • private and package private classes and members
  • Provisional API
    • packages with names *.provisional*
    • class that are marked EXPERIMENTAL and all its members
 EXPERIMENTAL. This class or interface has been added as part
 of a work in progress. There is no guarantee that this API will work or that
 it will remain the same.
  • Public API
    • everything which is not internal or provisional and
      • has public or protected java visibility
      • in public exported package
    • public API class or interface can also have some usage exceptions:
      • classes and members marked @noreference in the javadoc comment cannot be used and not considered public API even if they have public visibility
      • classes and interfaces that are marked as @noextend should not be extended
      • interfaces that are marked @noimplement should not be implemented

See also Evolving Java-based APIs.

Note: you can still use internal API is you want to, if java visibility allows you (even if it does not, you can hack it, using reflection). The only problem with this approach is that internal API can be changed without notice or trace, so you would have hard time making your code compile or run with new version of the tool. The best approach in this case to submit a bug asking to create an API for functionality you are looking for.

Using API Tooling

All committers and contributors should enable API Tooling when writing patches for CDT.
The previously recommended procedure to setup the tool for CDT was found to prevent the tool from reporting all errors. See here for the email exchange.
Below is the recommended procedure for the CDT, which is to install the version of the CDT to be used as a baseline into a separate copy of the corresponding Eclipse platform, and then point API tooling in your development installation of Eclipse to it:

  1. Download and unzip the eclipse version that matches the CDT version you want to use as a baseline. Here, we use Eclipse Luna 4.4.0.
  2. Download the official CDT release you are building a patch against from http://www.eclipse.org/cdt/downloads.php (here we want the latest Luna CDT, which is 8.4.0)
  3. Launch the eclipse platform you just installed and install the CDT archive you just downloaded:
    1. Help->Install New Software...
    2. Press Add... button
    3. Press Archive... button
    4. Choose the CDT zip file you just downloaded
    5. Unselect "Group items by category"
    6. Press "Select All"
    7. Continue until the CDT has been installed
    8. Close eclipse, you will not need to re-launch this copy of it anymore
  4. In you development eclipse go to Window->Preferences->Plug-in Development->API Baselines
  5. Press the "Add Baseline..." button
  6. Name your new baseline (e.g, CDT8.4)
  7. Choose the directory of the eclipse installation where you just installed CDT (4.4.0 + CDT 8.4.0)
  8. Make sure the new baseline is the selected one.

Once this is done, a full build will be triggered. After that, any changes that doesn't follow API rules will be shown as an error.

Javadoc

All public API classes and interfaces must have meaningful javadoc header, as well as all public API members.

Contributing to CDT

See CDT/contributing

Applying the Patch

  • Assign bug to yourself
  • Set target milestone field to release in which patch would be applied, If it is applied in two branches set target milestone to maintenance branch
  • Code inspect the patch, apply and test
  • Commit the patch
  • Set the iplog as follows:
    • to '-' if the patch came from a committer
    • to '+' if the patch came from a non-committer.
  • If the patch is > 1,000 lines, it must be submitted for IP review, i.e. CQ in IPZilla. See Development_Resources/Automatic_IP_Log
  • Check that all non-committed patches are marked as obsolete
  • Change bug state to fixed. Check again that you set milestone field.
  • Add a comment about where it was fixed (branches) and related notes

Committing Code

  • API changes have to be discussed in cdt-dev mailing list before commiting
  • When development reaches cycle where release candidates are built, letter in cdt-dev should be sent for every commit you are making
  • Have a bug associated with every commit, bug number at the begging of commit comment in form of
 Bug 12345 fixed that, added this
  • Post a change for review on gerrit
  • You may not need gerrit review if changes are cosmetic - formatting, warning fixed, copyright, auto-re factoring, typos in strings.

How to add a new feature

  • Create a feature project
  • Copy build.properties, epl-v10.html, feature.properties, feature.xml, license.html from another cdt feature plugin
  • Open in feature editor and modify all feature specific details including plugin list
  • Add it org.eclipse.cdt.releng/buildsite.xml (see how other are done)
  • Add in maps org.eclipse.cdt.releng/maps/cdt.map

How to add a new plugin

  • Create a new plugin plugin
  • Version should be like 1.0.0.qualifier
  • Edit name and vendor. Externalize string. Bundle-Vendor = Eclipse CDT
  • Add your plugin to a feature
  • Edit org.eclipse.cdt.releng/build.xml, add call to "tagone" target with your plugin path. See examples in the file.
  • Open project properties Java Compiler -> Error and Warnings. Check "Enable project specific settings". Go through list of warnings and set some to errors (see above list of recommended settings). Some people prefer zero warning tolerance, in this case all of them should be errors and no warnings.
  • Add in maps org.eclipse.cdt.releng/maps/cdt.map
  • Make sure all packages are exported (or x-exported). See http://wiki.eclipse.org/Export-Package
  • Check in all changed plugins

Version Numbering

See Eclipse Version Numbering Guildlines

Bugs Workflow

For creating and managing bugs see http://wiki.eclipse.org/CDT/Bugs