gradle-3.0.md

Gradle 3.0

Gradle 3.0 is the next major Gradle release that offers the opportunity to make breaking changes to the public interface of Gradle. This document captures a laundry list of ideas to consider before shipping Gradle 3.0.

Note: for the change listed below, the old behaviour or feature to be removed should be deprecated in a Gradle 2.x release. Similarly for changes to behaviour.

Candidates for Gradle 3.0

The following stories are candidates to be included in a major release of Gradle. Currently, they are not scheduled to be included in Gradle 3.0.

Test output directories

The current defaults for the outputs of tasks of type Test conflict with each other:

• Change the default result and report directory for the Test type to include the task's name, so that the default does not conflict with the default for any other Test task.
• Change the default TestNG output directory.

Log changes

• Remove --no-color command-line option.
• Remove LoggingConfiguration.colorOutput property.
• Remove LoggingManager.logLevel property. Managing the log level should not be a concern of the build logic.
• Remove Project.getLogging() method. Would be replaced by the existing logging property on Script and Task.
• Move internal types StandardOutputCapture, StandardOutputRedirector and LoggingManagerInternal into an internal package.

Archive tasks + base plugin

• Remove org.gradle.api.tasks.bundling.Jar, replaced by org.gradle.jvm.tasks.Jar.
• Move defaults for output directory and other attributes from the base plugin to an implicitly applied plugin, so that they are applied to all instances.
• Use ${task.name}.${task.extension} as the default archive name, so that the default does not conflict with the default for any other archive task.

Drop support for Gradle versions older than 1.0

• Cross version tests no longer test against anything earlier than 1.0
• Local artifact reuse no longer considers candidates from the artifact caches for Gradle versions earlier than 1.0
• Wrapper does not support downloading versions earlier than 1.0
• Remove old unused types that are baked into the bytecode of tasks compiled against older versions (eg ConventionValue). Fail with a reasonable error message for these task types.

Remove support for building against Java 5

Building against Java 5 requires that the compiler daemon and test execution infrastructure still support Java 5.

• Clean up DefaultClassLoaderFactory.
• Change InetAddressFactory so that it no longer uses reflection to inspect NetworkInterface.
• Replace usages of guava-jdk5.

Remove Ant based incremental compilation backend

Now we have real incremental Java compilation, remove the CompileOptions.useDepend property and related options.

Remove the Gradle Open API stubs

• Remove the remaining Open API interfaces and stubs.
• Remove the openApi project.

Remove group and status from project

Alternatively, default the group to null and status to integration.

Remove the Ant-task based Scala compiler

• Change the default for useAnt to false and deprecate the useAnt property.
• Do a better job of matching up the target jvm version with the scala compiler backend.

Don't inject tools.jar into the system ClassLoader

Currently required for in-process Ant-based compilation on Java 5. Dropping support for one of (in-process, ant-based, java 5) would allow us to remove this.

Decouple publishing DSL from Maven classes

• Change the old publishing DSL to use the Maven 3 classes instead of Maven 2 classes. This affects:
  • MavenResolver.settings
  • MavenDeployer.repository and snapshotRepository.
  • MavenPom.dependencies.
• Remove MavenDeployer.addProtocolProviderJars().
• Change PublishFilter so that it accepts a PublishArtifact instead of an Artifact.

Copy tasks

There are several inconsistencies and confusing behaviours in the copy tasks and copy spec:

• Change copy tasks so that they no longer implement CopySpec. Instead, they should have a content property which is a CopySpec that contains the main content. Leave behind some methods which operate on the file tree as a whole, eg eachFile(), duplicatesStrategy, matching().
• Change the copy tasks so that into always refers to the root of the destination file tree, and that destinationDir (possibly with a better name) is instead used to specify the root of the destination file tree, for those tasks that produce a file tree on the file system.
• Change the Jar type so that there is a single metaInf copy spec which is a child of the main content, rather than creating a new copy spec each time metainf is referenced. Do the same for War.webInf.
• The CopySpec.with() method currently assumes that a root copy spec is supplied with all values specified, and no values are inherited by the attached copy spec. Instead, change CopySpec.with() so that values are inherited from the copy spec.
  • Change CopySpec so that property queries do not query the parent value, as a copy spec may have multiple parents. Or, alternatively, allow only root copy spec to be attached to another using with().
• Change the default duplicatesStrategy to fail or perhaps warn.
• Change the Ear type so that the generated descriptor takes precedence over a descriptor in the main content, similar to the manifest for Jar and the web XML for War.

Remove old dependency result graph

The old dependency result graph is expensive in terms of heap usage. We should remove it.

• Promote new dependency result graph to un-incubate it.
• Remove methods that use ResolvedDependency and UnresolvedDependency.
• Keep ResolvedArtifact and replace it later, as it is not terribly expensive to keep.

Remove API methods that are added by the DSL decoration

Some model types hand-code the DSL conventions in their API. We should remove these and let the DSL decoration take care of this, to simplify these types and to offer a more consistent DSL.

• Remove all methods that accept a Closure when an Action overload is available. Add missing overloads where appropriate.
• Remove all methods that accept a String or Object when a enum overload is available. Add missing overloads where appropriate.
• Remove CharSequence -> Enum conversion code in DefaultTaskLogging.
• Remove all set methods that contain no custom logic.
• Formally document the Closure → Action coercion mechanism
  • Needs to be prominent enough that casual DSL ref readers understand this (perhaps such Action args are annotated in DSL ref)

Tooling API clean ups

• LongRunningOperation.withArguments() should be called setArguments() for consistency.
• Remove support for consumers older than 1.6, will allow the provider to drop support for BuildActionRunner protocol.
• Remove the old ProgressListener interfaces and methods. These are superseded by the new interfaces. However, the new interfaces are supported only by Gradle 2.5 and later, so might need to defer the removal until 4.0.
• Move UnsupportedBuildArgumentException and UnsupportedOperationConfigurationException up to org.gradle.tooling, to remove package cycle from the API.

Clean up Task DSL and hierarchy

• Remove the << operator.
• Inline ConventionTask and AbstractTask into DefaultTask.
• Remove Task.dependsOnTaskDidWork().
• Mix TaskInternal in during decoration and remove references to internal types.

Remove references to internal classes from API

• Remove Configurable from public API types.
• Remove PomFilterContainer.getActivePomFilters().
• Change StartParameter so that it no longer extends LoggingConfiguration.
• Move ConflictResolution from public API (it's only used internally).
• Move Module from public API (it's only used internally).
• Move Logging.ANT_IVY_2_SLF4J_LEVEL_MAPPER from public API.
• Move AntGroovydoc and AntScalaDoc from public API.
• Move BuildExceptionReporter, BuildResultLogger, TaskExecutionLogger and BuildLogger out of the public API.

Remove support for convention objects

Extension objects have been available for over 2 years and are now an established pattern.

• Migrate core plugins to use extensions.
• Remove Convention type.

Project no longer inherits from its parent project

• Project should not delegate to its build script for missing properties or methods.
• Project should not delegate to its parent for missing properties or methods.
• Project build script classpath should not inherit anything from parent project.

Container API tidy-ups

• Remove the specialised subclasses of UnknownDomainObjectException and the overridden methods that exist simply to declare this from PluginContainer, ArtifactRepositoryContainer, ConfigurationContainer, TaskCollection.
• Remove the specialised methods such as whenTaskAdded() from PluginCollection, TaskCollection
• Remove the extends T upper bound on the type variable of DomainObjectCollection.withType().
• Remove the type variable from ReportContainer
• Remove unused constants from ArtifactRepositoryContainer
• Move ReportContainer.ImmutableViolationException to make top level.

Dependency API tidy-ups

• Remove equals() implementations from Dependency subclasses.
• Remove ExternalDependency.force. Use resolution strategy instead.
• Remove SelfResolvingDependency.resolve() methods. These should be internal and invoked only as part of resolution.
• Remove ClientModule and replace with consumer-side component meta-data rules.
• Remove ExternalModuleDependency.changing. Use component meta-data rules instead.

Invocation API tidy-ups

• Remove the public StartParameter constructor.
• Remove the public StartParameter constants, GRADLE_USER_HOME_PROPERTY_KEY and GRADLE_USER_HOME_PROPERTY_KEY.
• Change StartParameter into an interface.

Misc API tidy-ups

• Replace TaskDependency.getDependencies(Task) with TaskDependency.getDependencies().
• Remove constants from ExcludeRule.
• Rename IllegalDependencyNotation to add Exception to the end of its name.
• Remove ConventionProperty, replace it with documentation.
• Remove Settings.startParameter. Can use gradle.startParameter instead.
• Remove org.gradle.util from default imports.
• Remove AbstractOptions.
• Remove or rename Logging.ANT_IVY_2_SLF4J_LEVEL_MAPPER.
• Remove unused EclipseDomainModel.
• Replace ShowStacktrace.INTERNAL_EXCEPTIONS with NONE.

Remove sonar plugin

Promote the sonar-runner plugin and remove the sonar plugin.

Signing plugin tidy-ups

• SignatoryProvider and sub-types should use container DSL instead of custom DSL.

Decorate classes at load time instead of subclassing

Decorating classes at load time is generally a more reliable approach and offers a few new interesting use cases we can support. For example, by decorating classes at load time we can support expressions such as new MyDslType(), rather than requiring that Gradle control the instantiation of decorated objects.

Switching to decoration at load time should generally be transparent to most things, except for clients of ProjectBuilder that refer to types which are not loaded by Gradle, such as the classes under test.

Restructure plugin package hierarchy

buildNeeded and buildDependents

• Rename buildDependents to buildDownstream
• Rename buildNeeded to buildUpstream
• Add a new task buildStream which is equivalent to buildDownstream buildUpstream

build.gradle in a multiproject build

• A Gradle best pattern is to name the gradle file to be the same name as the subproject.
• Let's support this out of the box, possibly as a preference to build.gradle, and maybe drop support for build.gradle in subprojects.