Embed Size (px)
Citation preview
www.devoxx.com
Overallpresenta3on
Introduc3ontoDomainSpecificLanguagesanditstechniques.AswellasshowingFluentValida3onFrameworkconcep3onprocess.
www.devoxx.com
DomainSpecificLanguage(DSL)isaprogramminglanguagededicatedtosolveproblemsofanspecificdomain
www.devoxx.com
whichcanbetechnical
SQL HQL CSS
www.devoxx.com
orbusinessrelated.
Banking Manufacturing
Logis3cs
www.devoxx.com
ADSLcanbeinternalorexternal.
www.devoxx.com
ExternalDSLsareself‐contained
www.devoxx.com
whileinternalDSLsremainontopofotherprogramminglanguages.
www.devoxx.com
Inotherwords,internalDSLsareAPIs.
That's why they're also known as Fluent Interfaces!
www.devoxx.com
DSLsallowyoutoexpressdomainsclearly.
www.devoxx.com
Forexample,whileabusinessanalystofabankingdomainwouldsay
Transfer 5.000,00 from Client A's cash account to Client B's savings account.
www.devoxx.com
AcommonJAVAimplementa3oncouldbe
bankService.transfer(5000.00, clientA.getCashAccount(), clientB.getSavingsAccount());
www.devoxx.com
AnexternalDSLcouldexpressthesameas
transfer 5000 from clientA.cashAccount to clientB.savingsAccount
www.devoxx.com
AndaninternalDSLinJAVAcouldlooklike
bankService.execute( new Transfer() .of(5000) .from(clientA.cashAccount()) .to(clientB.savingsAccount()));
www.devoxx.com
It’snotaboutonesinglemethod
publicTransferof(doublevalue);
www.devoxx.com
butanen3remeaningfulopera3on.
new Transfer() .of(5000) .from(clientA.cashAccount()) .to(clientB.savingsAccount())
www.devoxx.com
SometechniquestodefineinternalDSLs
www.devoxx.com
MethodChaining
new Transfer() .of(5000) .from(clientA.cashAccount()) .to(clientB.savingsAccount())
www.devoxx.com
NestedFunc3on
bankService.transfer(5000, from(clientA.cashAccount()), to(clientB.savingsAcount()));
www.devoxx.com
ObjectScoping
bankService.execute( new Transfer(){{ of(5000); from(clientA.cashAccount()); to(clientB.savingsAccount()); }});
www.devoxx.com
FluentValida3onFrameworkisalabprojectapplyingFluentInterfacestothe
domainofcodevalida3on.
www.devoxx.com
Mainideawaschangingvalida3onslike
if(arg0 == null) throw new IllegalArgumentException();
www.devoxx.com
tosomethinglike
ensure(arg0).isNotNull();
www.devoxx.com
Howtochangeexcep3onmessage?
ensure(arg0).isNotNull().otherwise("arg0 cannot be null"); //doesn't work
www.devoxx.com
Triggermethodattheendoftheexpression
ensure(arg0).isNotNull().now();
ensure(arg0).isNotNull() .otherwise() .throwThis( new IllegalStateException()) .now();
//not cool!
www.devoxx.com
Anotherop3onwascrea3ngtwoentrypoints
ensure(arg0).isNotNull();
analyse(arg0).and().throwThis(new IllegalStateException()).ifNull();
www.devoxx.com
Mixingmethodchainingwithnestedfunc3ons
ensure(myObject).is(inValidState());
analyse(systemReport).and(notifyByEmail()).ifIsNot(operatingWell());
thesolu3onbecameextensible!
www.devoxx.com
Todaywesaw
DSLsarecool! ExternalDSLsarehardtoimplement FluentInterfacesandInternalDSLsarethesamething FluentInterfacesworkgreatforextensivelyusedAPIs
www.devoxx.com
That’sallfolks!
projecthXp://fluval.sourceforge.net bloghXp://blog.danielgazineu.com
email/[email protected]
twiXer@danielgazineu
