Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License Francesco Cirillo – [email protected] MetodiAgili.it Javaday Roma - 01/12/2007.

Francesco Cirillo – [email protected] MetodiAgili.itJavaday Roma - 01/12/2007

Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License

Campagna Anti-IF:Java e i linguaggi dinamici, incrementare le potenzialità espressive di Java[“Eliminare” i FOR]



Campagna Anti-IF



Obiettivo

Più potere a Java “senza” i FOR Paper su come “eliminare” i FOR

Esperienza di design evolutivo Attraverso il refactoring Usando i principi di design

Far vincere qualche maglietta :)



Sviluppo Java Web: lento!

News [email protected]

http://it.groups.yahoo.com/group/extremeprogramming-it/message/4485:…> E poi detta tutta java a sviluppo web non è così tanto veloce in una> giornata non si riesce.

su questo no :-) Direi che una prima iterazione con tutte le funzionalita' di base in una giornata con 2 coppie si riesce a fare.

> Con Rails in mezza o 1/4 :) ma non entriamo in guerre di religione.

Se non si riesce probabilmente le storie non sono state spezzate in modo iterativo-incrementale/verticale ;-)…

http://it.groups.yahoo.com/group/extremeprogramming-it/message/4485:…> E poi detta tutta java a sviluppo web non è così tanto veloce in una> giornata non si riesce.

su questo no :-) Direi che una prima iterazione con tutte le funzionalita' di base in una giornata con 2 coppie si riesce a fare.

> Con Rails in mezza o 1/4 :) ma non entriamo in guerre di religione.

Se non si riesce probabilmente le storie non sono state spezzate in modo iterativo-incrementale/verticale ;-)…


Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License// class Departmentpublic void printSlips() {

Resource resource = null;for(int i=0; i < _resources.size();i++) {

resource = (Resource)_resources.get(i);if(resource.lastContract().deadline().after(new Date())) {

System.out.println(resource.name());System.out.println(resource.salary());

}}

}

// class Departmentpublic void printSlips() {




}}

}

Il problema

public void printSlips() {for (Resource eachResource: _resources) {

if(eachResource.lastContract().deadline().after(new Date()) ) {System.out.println(eachResource.name());System.out.println(eachResource.salary());

}}

public void printSlips() {for (Resource eachResource: _resources) {


}}

“Our job is to solve problems, not spoonfeed compilers (…)We need clarity so we can communicate using our code. We value conciseness and the ability to express a requirement in code accurately and efficiently”. --Dave Thomas


(resources select: inForce) do: printSlip.(resources select: inForce) do: printSlip.






}}

}





}}

}

Parliamo di design






}}

}





}}

}

Parliamo di design

public void printSlipForEach() {for (Resource eachResource: _resources) {


}}

}

public void printSlipForEach() {for (Resource eachResource: _resources) {


}}

}

Layout?Layout?Layout?Layout?

Selezione?Selezione?Selezione?Selezione?

Media?Media?Media?Media? Contenuti?Contenuti?Contenuti?Contenuti?

Ciclo?+Navigazione?Ciclo?+Navigazione?Ciclo?+Navigazione?Ciclo?+Navigazione?

Ciclo?Ciclo?Ciclo?Ciclo?



Il Refactoring: Aumentare la capacità del codice di rivelare

le intenzioni di design, a qualsiasi membro del team, alla prima occhiata

Migliorare la struttura interna del sistema, consentendo alle necessarie astrazioni di emergere

LightweightLightweightLightweightLightweight



Abbassare la complessità






}}

}





}}

}

Step 1: Separare le logiche


Stampa busta?Stampa busta?Stampa busta?Stampa busta?


Resource eachResource = null;List inforces = new ArrayList();for(int i=0; i < _resources.size();i++) {

eachResource = (Resource)_resources.get(i);if(eachResource.lastContract().deadline().after(new Date()) ) {

inforces.add(eachResource);}

}Resource eachInForce = null;for(int i=0; i < inforces.size();i++) {

eachInForce = (Resource)inforces.get(i);System.out.println(eachInForce.name());System.out.println(eachInForce.salary());

}}





}Resource eachInForce = null;for(int i=0; i < inforces.size();i++) {


}}



Step 2: Semplificare il FOR// class Departmentpublic void printSlips() {

……Resource eachInForce = null;for(int i=0; i < inforces.size();i++) {


}}




}}




}}




}}

Logica i-esimaLogica i-esimaLogica i-esimaLogica i-esima

Ciclo + navigazioneCiclo + navigazioneCiclo + navigazioneCiclo + navigazione

new Block() {public void evaluate(Resource each) {

System.out.println(each.name());System.out.println(each.salary());

}}.evaluate(eachInForce);

new Block() {public void evaluate(Resource each) {

System.out.println(each.name());System.out.println(each.salary());

}}.evaluate(eachInForce);





eachInForce = (Resource)inforces.get(i); new Block() {

public void evaluate(Resource each) {System.out.println(each.name());System.out.println(each.salary());

}}.evaluate(eachInForce);}

}



eachInForce = (Resource)inforces.get(i); new Block() {

public void evaluate(Resource each) {System.out.println(each.name());System.out.println(each.salary());

}}.evaluate(eachInForce);}

}







eachInForce = (Resource)inforces.get(i);new PrintSlip().evaluate(eachInForce);

}}




}}



public class PrintSlip implements Block {public void evaluate(Resource aResource) {

System.out.println(aResource.name());System.out.println(aResource.salary());

}}



}}





}}



}}

Step 3: Eliminare il FOR// class Departmentpublic void printSlips() {



}}




}}







}}



}}

Step 3: Eliminare il FOR// class Departmentpublic void printSlips() {

……Iterator iterator = inforces.iterator();while(iterator.hasNext()) {

new PrintSlip().evaluate(iterator.next());}

}



new PrintSlip().evaluate(iterator.next());}

}


CicloCicloCicloCiclo





}}



}}

Step 3: Eliminare il FOR// class Departmentpublic void printSlips(…) {


aBlock.evaluate(iterator.next());}

}

// class Departmentpublic void printSlips(…) {



}





Step 3: Eliminare il FORpublic class ResourceOrderedCollection {

private Collection _items;

public ResourceOrderedCollection(Collection items) {_items = items;

}

public void forEachDo(Block aBlock) {Iterator iterator = _items.iterator();while(iterator.hasNext()) {

aBlock.evaluate((Resource)iterator.next());}

}}

public class ResourceOrderedCollection {private Collection _items;

public ResourceOrderedCollection(Collection items) {_items = items;

}



}}

public void printSlips() {Resource eachResource = null;List inforces = new ArrayList();for(int i=0; i < _resources.size();i++) {



}new ResourceOrderedCollection(inforces).forEachDo(new PrintSlip());

}





}

NavigazioneNavigazioneNavigazioneNavigazione



Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Licensepublic void printSlips() {Resource eachResource = null;List inforces = new ArrayList();for(int i=0; i < _resources.size();i++) {




}





}

Step 4: E la selezionepublic void printSlips() {





}





}


eachResource = (Resource)_resources.get(i);if(new PredicateBlock() {

public boolean is(Resource each) {return each.lastContract().deadline().after(new Date());

}}.is(eachResource) {inforces.add(eachResource);

}}new ResourceOrderedCollection(inforces).forEachDo(new PrintSlip());

}


eachResource = (Resource)_resources.get(i);if(new PredicateBlock() {

public boolean is(Resource each) {return each.lastContract().deadline().after(new Date());

}}.is(eachResource) {inforces.add(eachResource);

}}new ResourceOrderedCollection(inforces).forEachDo(new PrintSlip());

}


SelezioneSelezioneSelezioneSelezione

AddizioneAddizioneAddizioneAddizioneLogica i-esimaLogica i-esimaLogica i-esimaLogica i-esima



Step 4: E la selezionepublic void printSlips() {


eachResource = (Resource)_resources.get(i);if(new InForcePredicate().is(eachResource)) {



}


eachResource = (Resource)_resources.get(i);if(new InForcePredicate().is(eachResource)) {



}

public class InForcePredicate implements PredicateBlock {public boolean is(Resource each) {

return each.lastContract().deadline().after(new Date());}

}



}



AddizioneAddizioneAddizioneAddizione



Step 4: E la selezione

public void printSlips() {Collection inforces = new ResourceOrderedCollection(_resources).select(new InForce());new ResourceOrderedCollection(inforces).forEachDo(new PrintSlip());

}


}

public Collection select(PredicateBlock aBlock) {Collection result = new ArrayList();Iterator iterator = _items.iterator();while(iterator.hasNext()) {

Resource resource = (Resource)iterator.next();if (aBlock.is(resource)) result.add(resource);

}return result;

}

public Collection select(PredicateBlock aBlock) {Collection result = new ArrayList();Iterator iterator = _items.iterator();while(iterator.hasNext()) {


}return result;

}



}



}


AddizioneAddizioneAddizioneAddizione


NavigazioneNavigazioneNavigazioneNavigazione



Step 5: Per leggere megliopublic void printSlips() {

Collection inforces = new ResourceOrderedCollection(_resources).select(new InForce());new ResourceOrderedCollection(inforces).forEachDo(new PrintSlip());

}


}public void printSlips() {

(new ResourceOrderedCollection(_resources).select(new InForce()).forEachDo(new PrintSlip()); }

public void printSlips() {(new ResourceOrderedCollection(_resources).select(new InForce()).forEachDo(new PrintSlip());

} public ResourceOrderedCollection select(PredicateBlock aBlock) {

ResourceOrderedCollection result = new ResourceOrderedCollection();Iterator iterator = _items.iterator();while(iterator.hasNext()) {


}return result;

}

public ResourceOrderedCollection select(PredicateBlock aBlock) {ResourceOrderedCollection result = new ResourceOrderedCollection();Iterator iterator = _items.iterator();while(iterator.hasNext()) {


}return result;

}

public void printSlips() {Predicate isInForce = new InForce();Block printSlip = new PrintSlip();ResourceOrderedCollection resources = new ResourceOrderedCollection(_resources);resources.select(isInForce).forEachDo(printSlip);

}


}



Step 5: Per leggere meglio


}


}

public void printSlipsUsing(Predicate aCriterium, Block anAction) {_resources.select(aCriterium).forEachDo(anAction);

}

public void printSlipsUsing(Predicate aCriterium, Block anAction) {_resources.select(aCriterium).forEachDo(anAction);

}

private ResourceOrderedCollection _resources;private ResourceOrderedCollection _resources;

public void printSlips() {printSlipsUsing(new InForce(),new PrintSlip());

}

public void printSlips() {printSlipsUsing(new InForce(),new PrintSlip());

}

private void printSlipsUsing(Predicate aCriterium, Block anAction) {new ResourceOrderedCollection(_resources).select(aCriterium).forEachDo(anAction);

}

private void printSlipsUsing(Predicate aCriterium, Block anAction) {new ResourceOrderedCollection(_resources).select(aCriterium).forEachDo(anAction);

}



Step 6: Generalizzare

new ResourceOrderedCollection(resources).select(isInForce).forEachDo(printSlip); new ResourceOrderedCollection(resources).select(isInForce).forEachDo(printSlip);

public class ResourceOrderedCollection {…public void forEachDo(Block aBlock) {

Iterator iterator = _items.iterator();while(iterator.hasNext()) {


}public ResourceOrderedCollection select(Predicate aBlock) {

ResourceOrderedCollection result = new ResourceOrderedCollection();



}return result;

}}








}return result;

}}



}}



}}



}



}



Step 6: Generalizzare

new ResourceOrderedCollection(resources).select(isInForce).forEachDo(printSlip); new ResourceOrderedCollection(resources).select(isInForce).forEachDo(printSlip);








}return result;

}}








}return result;

}}

public class OrderedCollection {…public void forEachDo(Block aBlock) {



}public OrderedCollection select(Predicate aBlock) { OrderedCollection result =

new OrderedCollection();Iterator iterator = _items.iterator();while(iterator.hasNext()) {

Object object = iterator.next();if (aBlock.is(object)) result.add(object);

}return result;

}}

public class OrderedCollection {…public void forEachDo(Block aBlock) {



}public OrderedCollection select(Predicate aBlock) { OrderedCollection result =

new OrderedCollection();Iterator iterator = _items.iterator();while(iterator.hasNext()) {


}return result;

}}



}}



}}



}



}

public class PrintSlip implements Block {public void evaluate(Object anObject) {

System.out.println(((Resource)anObject).name());System.out.println(((Resource)anObject).salary());}

}


System.out.println(((Resource)anObject).name());System.out.println(((Resource)anObject).salary());}

}

public class InForcePredicate implements Predicate {public boolean is(Object anObject) {

return ((Resource)anObject).lastContract().deadline().after(new Date());}

}

public class InForcePredicate implements Predicate {public boolean is(Object anObject) {

return ((Resource)anObject).lastContract().deadline().after(new Date());}

}



Dove siamo// class Departmentpublic void printSlips() {




}}

}





}}

} Layout?Layout?Layout?Layout?

Contenuti?Contenuti?Contenuti?Contenuti?

Navigazione?Navigazione?Navigazione?Navigazione?


Media?Media?Media?Media?

NavigazioneNavigazioneNavigazioneNavigazione SelezioneSelezioneSelezioneSelezioneContenuti+Contenuti+

Media+Media+LayoutLayout

Contenuti+Contenuti+Media+Media+LayoutLayout

_resources.select(isInForce).forEachDo(printSlip); _resources.select(isInForce).forEachDo(printSlip); _resources.select(onlyWomen).forEachDo(printReport); _resources.select(onlyWomen).forEachDo(printReport);



Review & ToDoList

:Department

Andrea:Employee

Federica:Manager

10/01-10/11/2007:Contract

1/9/2007-10/10/2008:Contract

“Federica”:String

“Andrea”:String





}}

}





}}

}Layout?Layout?Layout?Layout?

Contenuti?Contenuti?Contenuti?Contenuti?

Navigazione?Navigazione?Navigazione?Navigazione?


Media?Media?Media?Media?

System.out:PrintStream



Review & ToDoList

resources:OrderedCollection

:Department

Andrea:Employee

Federica:Manager

10/01-10/11/2007:Contract

1/9/2007-10/10/2008:Contract

:InForce

:PrintSlip



inForce:OrderedCollection

“Andrea”:String

_resources.select(isInForce).forEachDo(printSlip); _resources.select(isInForce).forEachDo(printSlip);

public OrderedCollection select(Predicate aBlock) { OrderedCollection result = new OrderedCollection();



}return result;

}




}return result;

}

public boolean is(Object each) {return ((Resource)each).lastContract().deadline().after(new Date());

}

public boolean is(Object each) {return ((Resource)each).lastContract().deadline().after(new Date());

}



Review & ToDoList

resources:OrderedCollection

:Department

Andrea:Employee

Federica:Manager

10/01-10/11/2007:Contract

1/9/2007-10/10/2008:Contract

:InForce

:PrintSlip



inForce:OrderedCollection

“Andrea”:String



}



}




}return result;

}




}return result;

}


System.out.println(((Resource)anObject).name());System.out.println(((Resource)anObject).salary());

}}


System.out.println(((Resource)anObject).name());System.out.println(((Resource)anObject).salary());

}}



Riferimenti blocchi e chiusure

Blocchi in Java http://www.c2.com/cgi/wiki?BlocksInJava

Blocchi e chiusure in Ruby http://www.artima.com/intv/closuresP.html

Chiusure nel linguaggio Java http://www.javac.info/closures-v03.html

Esempi di librerie http://jaggregate.sourceforge.net



Segui la Campagna Anti-IF



Risorse:http://www.xplabs.it/risorse.htmlhttp://www.metodiagili.it/campagna-anti-if.html

Tecnica del Pomodoro: http://www.tecnicadelpomodoro.it

EasyTracking: http://www.myagileprojects.com

Gruppo XPLabs’ Friends- Italia:http://it.groups.yahoo.com/group/xplabs-friends/

Extreme Programming User Group – Italia:http://www.xpug.it/

Domande

Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License Francesco Cirillo – [email protected] MetodiAgili.it Javaday Roma - 01/12/2007.

Documents

resource resource

resource eachresource

null forint i

afternew date

javaday roma

license francesco cirillo

dave thomas resources

geti ifresource