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GR8Conf 2011: GContracts
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GR8Conf 2011: GContracts

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GR8Conf 2011: GContracts GR8Conf 2011: GContracts Presentation Transcript

  • GContractsAndre Steingress @sternegross/@gcontracts
  • LINZ, AUSTRIA
  • www.ejug.at
  • ABOUTGCONTRACTS.
  • GCONTRACTSDESIGN BY CONTRACT (tm) FOR GROOVY Groovy 1.7+ (was 1.6 loooong time ago)BSD LICENSEhttps://github.com/andresteingress/gcontracts
  • JUMP START.
  • LET‘S REVIEW THIS ACCOUNT CLASS.Googled, found at javacoffeebreak.com
  • PREREQUISITES.
  • @Grab( group=org.gcontracts, module=gcontracts-core, version=[1.2.3,)) no additional dependencies...
  • import org.gcontracts.annotations.*
  • 3 ANNOTATIONS.
  • Commonalities• special assertion types • specifying boolean expressions• closure instances as annotation parameters @MyAnnotation({ param?.size() > 0 })
  • @Requires• precondition• a method‘s bouncer
  • @Ensures• postcondition• a method‘s mother
  • @Invariant• class-invariant• an object‘s god.
  • LET‘S REVIEW THIS ACCOUNT CLASS.Googled, found at javacoffeebreak.com
  • INTERNALS.
  • @Ensures({ count() == old.count + 1 }) { count() == old.count + 1 } { result, old -> assert count() == old.count + 1 }compile-time class $_gc_closure1 extends Closure { def doCall(...) { // ... assert count() == old.count + 1 // ... } } @Requires($_gc_213123123123.class)
  • JVM Arguments: -ea -da if ($GCONTRACTS_ENABLED) { ... } org.gcontracts.ViolationTracker.init() $_gc_result = Putable$_gc_closure1.newInstance(this,run-time this).call(element, key) if (org.gcontracts.ViolationTracker.violationsOccured()) org.gcontracts.ViolationTracker.rethrowFirst()
  • Officially Supported since Groovy 1.8!
  • Works since Groovy 1.6http://pniederw.wordpress.com/2010/03/04/3/
  • MORE FEATURES.
  • LABELING
  • INTERFACE CONTRACTS
  • INTERFACE CONTRACTS
  • INHERITANCE✓INTERFACE CONTRACTS✓ABSTRACT CLASSES✓CONCRETE CLASSES✓MIXED
  • INHERITANCE✓ACROSS COMPILATION UNITS
  • MICRO CONTRACTS REUSABLE CONTRACT PART
  • MICRO CONTRACTS
  • Grails Integration• Container extends object construction time• @Service stereotype causes CI validation in @PostConstruct
  • GroovyDoc Integration
  • https://github.com/andresteingress/gcontracts/wiki
  • ABOUTCONTRACTS.
  • MR.„DESIGN BY CONTRACT“
  • WHY CONTRACTS?
  • SPOCK, JUNIT, et. al. ARE„THE CHINAMAN ISNOT THE ISSUE HERE, DUDE.“
  • External API Changes New Programmers Changing Requirements Assumptions Additional Libraries New Use-Cases More Clients New Knowledge Code Conventions
  • External API Changes New Programmers Changing Requirements Assumptions Additional Libraries New Use-Cases More Clients New Knowledge Code Conventions
  • WHAT DID YOU PROGRAM LAST WEEK?CAN YOU RECALL YOUR THOUGHTS, MODELS?WHY SHOULD ANYONE ELSE KNOW ABOUT THEM?
  • BUILD YOUR PLAYGROUND.
  • http://about.me/asteingress
  • Thank you!
  • "Design by Contract" is a trademark of Interactive Software Engineering.