book

Groovy for Domain-Specific Languages, Second Edition

by Fergal Dearle

September 2015

Intermediate to advanced

386 pages

8h 3m

English

Packt Publishing

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What this book covers

Downloading the example codeErrataPiracyQuestions
DSL – a new name for an old ideaThe evolution of programming languagesGeneral-purpose languagesSpreadsheets and 4GLsLanguage-oriented programmingWho are DSLs for?A DSL for process engineersStakeholder participationDSL design and implementationExternal versus internal DSLsOperator overloading
A natural fit with the JVMGroovy language featuresStatic and optional typingNative support for lists and mapsClosuresGroovy operator overloadingRegular expression supportOptional syntaxGroovy markup
Installing Groovy with GVMInstalling GVMInstalling GVM on Windows
The Groovy script engine – groovyShebang scriptsThe Groovy shell – groovyshThe Groovy console – groovyConsoleThe Groovy compiler – groovyc
NetBeansEclipseSpring STSIntelliJ IDEAOther IDEs and editors
Installing Gradle
Gradle build scriptsGradle tasksAdding actions to tasksDefault tasksCreating task dependenciesBuilt-in tasks and pluginsPluginsThe Gradle Groovy pluginThe IDEA pluginThe Eclipse pluginRepositoriesDependencies
Given, when, thenSpock specification structureFeature methodsBlocksFieldsFixture methodsHelper methodsWhere blocksFixture blocksTesting Gradle using Spock
Introducing the Groovy languageThe module structureGroovy shorthandImplicit importsDefault visibility, optional semicolonOptional parenthesesThe optional dot in method chainsDynamic typesThe optional return keywordProperties and GroovyBeansAssertionsAutoboxingStringsRegular expressionsMethods and closuresControl structuresGroovy TruthTernary and Elvis operatorsSpaceship and Elvis operatorsThe switch statementLoopsCollectionsRangesListsMapsOperatorsSpread and spread-dotNull safe dereferenceOperator overloading
What is a closure?
Method parameters as DSLForwarding parameters
The implicit doCall method
Enforcing zero parametersParameters and the doCall methodPassing multiple parametersDefault parameter valuesImplementing closures in JavaCurried parameters
The this, owner, and delegate variablesClosure compositionClosure trampolineClosure memoization
Twitter
Using Twitter4J Java APIsTweetingDirect messagesSearchingFollowing
A Groovier way to find friendsGroovy searching
RefactoringFleshing out GeeTwitterImproving search
Named parametersNamed parameters in DSLs
The builder design patternUsing Groovy buildersMarkupBuilderNamespaced XMLThe GroovyMarkup syntaxGroovyMarkup and HTMLUsing program logic with buildersBuilders for every occasionNodeBuilderUsing GPath to navigate a node tree
ReflectionGroovy reflection shortcutsExpandosCategoriesTraitsMetaClassPretended methods – MetaClass.invokeMethodUnderstanding this, delegate, and owner
Replacing methodsAdding or overriding static methodsDynamic method namingAdding overloaded methodsAdding constructors
What is an AST
Build from codeBuild from SpecTraits to the rescue
A finite state machine DSLThe state machine patternA state machine AST transformationHandling errors – compile errorsBuilding the new AST nodesTesting the state machine DSLCompiling and packaging an AST transformation
Grails object relational mapping – GORMGrails quick startThe grails-app directoryBuilding a GORM modelUsing domain classesModeling relationshipsAssociationsOne-to-oneConstraintsOne-to-manyMany-to-manyCompositionInheritanceMappingQueryingDynamic findersGORM as a DSL
SpockJUnit
The builder code structureClosure method callsThe resolve strategy – OWNER_FIRSTPretended methodsinvokeMethodmethodMissingThe closure delegate
BuilderSupport hook methodsA database builder
Groovy bindingsExploiting bindings in DSLsClosures as built-in methodsClosures as repeatable blocksUsing a specification parameterClosures as singleton blocksUsing binding properties to form contextStoring and communicating results
Designing the DSLBroadbandPlusReward typesThe reward DSLHandling events – deferred executionConvenience methods and shorthandThe offersThe RewardService classThe BroadbandPlus application classesTesting with Spock
Groovy as a teaching languageHiding complexity
Architecture and technology choicesTicTacToe in a DSLImplementing the AST transformBuilding the game engine patternTesting the DSLClass loading issuesGradle subprojectsDebuggingThe game serverIntegrating with Spring Boot serverController annotationsJSONPLoading the DSLSpring Data mapping for MongoDBThe Game UI

Overview

Groovy for Domain-Specific Languages, Second Edition is your guide to creating robust mini-languages using Groovy. Through practical examples and step-by-step instructions, this book introduces you to the world of DSLs, giving you the tools to build custom, problem-focused scripting solutions integrated with Java and JVM-based applications.

What this Book will help me do

Understand Groovy's fundamentals and scripting capabilities.
Master Groovy's metaprogramming features including closures and ASTs.
Utilize Groovy builders and markup for seamless application structuring.
Learn to create and leverage custom operators and command chains in Groovy.
Integrate Groovy DSLs effectively with Java projects.

Author(s)

None Dearle, an experienced developer and advocate for practical coding standards, brings years of expertise in JVM-based languages to this detailed exploration of Groovy DSLs. Dearle emphasizes real-world applications and teaches in a way that empowers readers to implement what they've learned directly into their projects. Their approach is methodical and example-driven, making even the complex seem accessible.

Who is it for?

This book is tailored for Java developers eager to expand their toolkit with Groovy-based DSLs. Whether you're a seasoned coder or a beginner in Groovy, this book bridges the gap by gradually introducing concepts from the basics to advanced topics like AST transformations. If you're looking to make your Java applications more versatile and elegant using Groovy, this book will guide you every step of the way.