DDDをScalaでどうやって実装していくかという話題。前半はScalaの適当な紹介と、その後にDDDのビルディングブロックをScalaコード上に反映するにはどうするかって話です。残りのサンプルは時間がなくて説明していません。すみません。

1. DDD + Scala
(@j5ik2o)

2. DDD , Scala , DSL , ...
DDD 2 (4,5,6 )
@j5ik2o

3. agenda
Scala DDD
Scala
DDD + Scala
DSL
JavaBeans

4. Scala

5. Scala
Scala
.scala .class
Java

6. Scala vs Java
Money Scala }
public BigDecimal getAmount() {
case class Money(amount :
BigDecimal, currency : Currency) return amount;
Money Java }
public class Money { public Currency getCurrency() {
private final BigDecimal amount; return currency;
}
private final Currency currency;
public Money(BigDecimal amnt, / equals, hashCode
/
Currency creny) { (ry
amount = amt;
}
currency = creny;

7. Hello, World!!
object HelloWorld{
def main(args: Array[String]):Unit = {
println(“Hello, World!!”)
}
}

8. val
scala> val name = "Junichi Kato"
name: java.lang.String = Junichi Kato
scala> name = "JUNICHI KATO"
<console>:6: error: reassignment to val
name = "JUNICHI KATO"

9. var
scala> var name = "Junichi Kato"
name: java.lang.String = Junichi Kato
scala> name = "JUNICHI KATO"
name: java.lang.String = JUNICHI KATO

10. type
scala> val name = "Junichi Kato"
name: java.lang.String = Junichi Kato
scala> val name:String = "Junichi Kato"
name: String = Junichi Kato
scala> val num:Number = 100L
num: java.lang.Number = 100

11. method
def add(a:Int, b:Int):Int = {
return a + b
}
def add(a:Int, b:Int):Int = a + b
def add(a:Int, b:Int) = a + b
hoge.add(1, 2) / 3
/

12. if & for
if
val a = 10
val ret = if (a % 2 == 0) true else false
val ret = if (a % 2 == 0) { println(“ ”); true }
else { println(“ ”); false }
def isEven(n: Int) = if (n % 2 == 0) true else false
for
for(i <- 1 to 3) println(i) / 1,2,3
/
for(i <- Array(1,2,3)) println(i) / 1,2,3
/
val numbers = for(i <- 1 to 10) yield i

13. class
class PersonName
(fn: String, ln: String){
require(fn.length > 0) // IAE
require(ln.length > 0) // IAE
val firstName = fn
val lastName = ln
def fullName = “%s, %s”.format(firstName, lastName)
}

14. class
class PersonName(val firstName:String, val
lastName: String){
require(firstName.length > 0)
require(lastName.length > 0)
def fullName = “%s, %s”.format(firstName,
lastName)

15. class
val pn = new PersonName(“Junichi”, “Kato”)
println(pn.fullName)
val pn2 = new PersonName(“”, “Kato”) / IAE
/

16. object
object EmployeeDao {
val DEFAULT_NAME = ...
def findAll = ...
}
val result = EmployeeDao.findAll
val defaultName = EmployeeDao.DEFAULT_NAME

17. { , }
class Money(val amount:BigDecimal, val currency: Currency) ...
object Money {
val JPY = Currency.getInstance(“JPY”)
def apply(amount: BigDecimal, currency: Currency) = new
Money(amount, currency)
}
val money:Money = Money(100, Money. JPY)
/ val money:Money = Money.apply(100, Money.JPY)
/

18. match
def numberMatch(n:Int) = n match {
case 1 => “one”
case 2 | 3 => “t wo or three”
case _ => “other”
}
println(numberMatch(1)) / one
/
println(numberMatch(2)) / t wo or three
/
println(numberMatch(3)) / t wo or three
/
println(numberMatch(4)) / other
/

19. match
val pattern = """([a-z]+)""".r case Array(1,2,3) => println(“
def matchTest(word: Any) = word 1,2,3 ”)
match {
case _ => throw new
case “ABC” => println(“ABC ”) IllegalArgumentException
case pattern(s) => println(" }
= "+s) matchTest(“ABC”) / ABC
/
case s: String => println(“ matchTest("aaaa") // =
= (%s)”.format(s)) (aaaa)
case n: Int if (n >= 2) => println(“2 matchTest(10) / 2
/
”)
matchTest(Array(1,2,3)) //
1,2,3

20. (a:Int) => a * a
val square: (Int) => Int = (a:Int) => a * a
val square = (a:Int) => a * a
val result = square(2) / 4
/

21. object MyMath {
def add(a:Int, b:Int) = a + b
}
val f1 = MyMath.add _
val f2: (Int,Int) => Int = MyMath.add

22. Collection
val il1 = List(1,2,3)
val il2 = list :+ 4 / 1,2,3,4
/
val im1 = Map(1 -> “ 2 -> “b”, 3 -> “c”)
a”,
val im2 = m1 + (4 -> “d”) / 1 -> “ 2 -> “b”, 3 -> “c”, 4 -> “d”
/ a”,
val ml = ListBuffer(1,2,3)
ml += 4
val mm = collection.mutalble.Map(1 -> “ 2 -> “b”, 3 -> “c”)
a”,
mm += (4 -> “d”)

23. Collection
val numbers = List(1,2,3,45)
numbers.foreach((n:Int) => println(n) ) / (1)
/
numbers.foreach(n => println(n)) / (2)
/
numbers.foreach(_ => println(_)) / (3)
/
numbers.foreach(println(_)) / (4)
/
numbers.foreach(println) / (5)
/
varl map = Map(1 -> “ 2 -> “b”)
a”,
map.foreach(entry => println(“key = %s, value =
%s”.format(entry._1,entry._2)))

24. Collection
val evens = numbers.filter(_ % 2 == 0) //
numbers
val list = List(1,2,3).map(_ * 2) / 2,4,6
/

25. Collection
Range ( (Seq) )
val range = 1 to 10; range.foreach(println)
for(i <- 1 to 10 by 2) println(i) / 1 3 5 7 9
/
6 FizzBuzz
(1 to 100).map{
case n if (n % 15 == 0) => “FizzBuzz”
case n if (n % 3 == 0) => “Fizz”
case n if (n % 5 == 0) => “Buzz”
case n => n
}.foreach(println)

26. trait
trait Greeting { def greet:Unit }
class JapaneseGreeting extends Greeting {
def greet = println(“ ”)
}
class EnglishGreeting extends Greeting {
def greet = println(“Hello”)
}
mix-in
trait Logging { def log(msg: String) = println(msg) }
class Employee(name:String) extends AbstractEmployee with
Logging {
log(“name = “+name)
}

27. DDD + Scala

28. Domain Object &
Lifecycle

29. Entity
trait Entity {
val id: String // OK
def equals(other: Any) = other match {
case that: Entity => id == that.id
case _ => false
}
def hashCode = id.hashCode
}

30. Entity
class Employee(val id: String, val name:
String)extends Entity
val kato1 = new Employee(“1”, “Junichi Kato”)
val kato2 = new Employee(“2”, “Junichi Kato”)
val kato3 = new Employee(“3”, “JUNICHI KATO”)
assert(kato1 != kato2)
assert(kato1 == kato3)

31. Entity with Factory
class Employee object Employee{
(val id:String, def apply(id:String,
name:String,
var name:String, dept:Department) = new
var dept:Department) Employee(id, name, dept)
extends Entity }

32. Entity with Factory
val kato = Employee(“KATO”,
Department(“DEV”))

33. Value Object with Factory
class Money override def toString =
"Money(%s, %s)".format(amount,
(val amount: BigDecimal, currency)
val currency: Currency){ }
override def equals(that: Any): object Money {
Boolean = that match {
def apply(amount: BigDecimal,
case other: Money => amount == currency: Currency) = new
other.amount && currency == Money(amount, currency)
other.currency
def unapply(money: Money) =
case _ => false Some(money.amount,
} money.currency)
override def hashCode = }
amount.hashCode +
currency.hashCode

34. Value Object with Factory
VO
assert(Money(100, Money.JPY) == Money(100, Money.JPY))
assert(Money(100, Money.JPY) != Money(105, Money.JPY))
assert(Money(100, Money.JPY) != Money(100, Money.USD))
unapply
val Money(amt, cry) = money1_100yen
println(“
amount = %s, currency = %s”.format(amt, cry))
money1_100yen match { / match
/
case Money(amt, cry) => println(“
amount = %s, currency = %s”.format(amt,
cry))
case _ => ()
}

35. Value Object(case class)
case class Money(amount: BigDecimal, currency:
Currency)
apply, unapply
val
toString, equals, hashCode
VO case class Money(amount:
BigDecimal, currency: Currency) extends ValueObject

36. ValueObject Builder
case class PersonName(firstName: String, lastName:
String)
class PersonNameBuilder extends
ValueObjectBuidler[PersonName, PersonNameBuilder] { ... }
VO
val personName1 = new
PersonNameBuilder().withFirstName("Junichi").withLastNa
me("Kato").build
val personName2 = new
PersonNameBuilder().withLastName(lastName.toUpperCase
).build(personName1)

37. Service
object TransferSer vice {
def transfer(money: Money,
from:BankAccount, to:BankAccount) =
to.push(from.pull(money))
}
TransferService.transfer(Money(1000,JPY),
BankAccount(“012345”),
BankAccount(“543210”))

38. Aggregate
class Employee(val id:String, var name:String, var dept:
Department) extends Entity
Employee id, name, dept

39. Aggregate
Department ( )
class Employee(val id:String, var name:String, var dept:
Department) extends Entity
class Department(val id: String, var name: String) extends Entity
val dept = Department(“1:1”, “DEV)
val emp = Employee(“1”, “KATO”, dept) / (1)
/
dept.name = “SALES” / (1)
/
val dept = emp.dept / (2)
/
dept.name = “SALES” / (2)
/

40. Aggregate(Cloneable)
@cloneable }
class Department(val id: String, var name: override def clone = { / (4)
/
String) extends Entity {
val result =
override def clone = super.clone.asInstanceOf[Employee]
super.clone.asInstanceOf[Department]
result.dpt = dpt.clone
}
}
@cloneable
}
class Employee(val id:String, var
val dept = Department(“1:1”, “DEV”)
name:String, _dpt: Department) extends
Entity { val emp = Employee(“1”, “KATO”, dept) / (1)
/
private var dpt = _dpt.clone / (1)
/ dept.name = “SALES”
def dept = dpt.clone / getDept
/ (2) val dept = emp.dept / (2)
/
def dept_= (value: Deaprtment) { // dept.name = “SALES”
setDept emp.dept = Department(“1:1”, “SALES”) / (3)
/
dpt = value.clone / (3)
/ val cloneEmp = emp.clone / (4)
/

41. Aggregate(clone)
clone Mix-in
@cloneable
trait EntityCloneable[T <: Entity] {
this: Entity =>
override def clone: T =
super.clone.asInstanceOf[T]
}

42. Aggregate(clone)
class Employee
(val id: String,
var name: String)
extends Entity with
EntityCloneable[Employee]
val emp = Employee(“1”, “Kato”)
val cloneEmp = emp.clone

43. Aggregate(Factory)
Factory
object Department {
def apply(dept: Department) =
new Department(dept, dept.name)
}
object Employee {
def apply(emp: Employee) =
new Employee(emp.id, emp.name, Department(emp.dept))
}
val emp = Employee(“1”, “KATO”, Department(“1:1”, “DEV”))
val cloneEmp = Employee(emp)

44. Repository
trait EntityResolver[T <: Entity] extends Iterable[T]
{
def resolve(id: String): T
def apply(id: String) = resolve(id)
def contains(id: String): Boolean = exists(_.id == id)
def contains(entity: T): Boolean = exists(_ == entity)
}

45. Repository
class EmployeeResolver extends val er = new EmployeeResolver
EntityResolver[Employee] {
val employee = er.resolve(id)
private val employees =
val employee = er(id) / er.apply
/
Map(“1” -> Employee(“1”,
-> resolve
“KATO”, Department(“1:1”,
“DEV”))) val employee = er.contains(id)
def resolve(id: String) = val exists = er.exists(_.name ==
employees(id) “KATO”)
def iterator = val employees =
employees.map(e => er.filter(_.name.startWith(“K”))
e._2.clone).iterator
er.foreach(println)
}

46. Repository
trait Repository[T <: Entity] extends
EntityResolver[T] {
def store(entity: T)
def update(identifier: Identifier, entity:T) =
store(entity)
def delete(identity: Identifier)
def delete(entity: T)
}

47. Repository
class EmployeeRepository / resolve, iterator ...
/
extends
Repository[Employee] { }
private val employees = val er = new
collection.mutalble.Map.emp EmployeeRepository
ty[String, Employee] val emp = Employee(id,
def store(emp: Employee) = “KATO”, Department(“DEV))
employees += (emp.id -> emp) er.store(emp)
def delete(id: String) = er(id) = emp
employee -= emp.id
er.delete(id)
def delete(emp: Employee) =
delete(emp.id) er.delete(emp)

49. ( )=
id(4a74c322-08ab-450b-b674-793e1d7f399a) = class
Department {
package = dept
fields {
name = java.lang.String
}
}

50. package dept;
public class Department {
private java.lang.String name;
public void setName(java.lang.String name){
this.name = name;
}
public java.lang.String getName(){
return name;
}
}

51. (.ftl)
<#if classMeta.getPackageName()??> <#assign getter = "is"/>
package ${classMeta.getPackageName()}; <#elseif f.getTypeName() ==
"java.lang.Boolean">
</#if>
<#assign getter = "is"/>
public class ${classMeta.getName()} {
<#else>
<#list classMeta.getFieldMetas() as f>
<#assign getter = "get"/>
private ${f.getTypeName()} $
{f.getName()}; </#if>
public void set${f.getName()?cap_first} public ${f.getTypeName()} ${getter}$
(${f.getTypeName()} ${f.getName()}){ {f.getName()?cap_first}(){
this.${f.getName()} = $ return ${f.getName()};
{f.getName()};
}
}
</#list>
}
<#if f.getTypeName() == "boolean">

52. codegen -h
codegen -c sample.config -t template -e export
codegen -c [4a74c322-08ab-450b-
b674-793e1d7f399a]@sample.config -t
template -e export

53. ClassMeta
FieldMeta
CodeGenSer vice
Factory
ClassMetaRepository

54. ClassMeta Entity
package codegen.domain
class ClassMeta
(@BeanProperty val identifier: Identifier, @BeanProperty val name:
String,
val packageName: Option[String], val fieldMetas: List[FieldMeta])
extends Entity {
override def toString: String = "ClassMeta(%s, %s, %s,
%s)".format(identifier, name, packageName, fieldMetas)
def getPackageName(): String = if (packageName.isEmpty) null else
packageName.get
def getFieldMetas(): java.util.List[FieldMeta] = fieldMetas.asJava
}

55. ClassMeta Object
object ClassMeta {
def apply(identifier: Identifier, name: String, packageName: Option[String],
fieldMetas: List[FieldMeta]) =
new ClassMeta(identifier, name, packageName, fieldMetas)
def apply(name: String, packageName: Option[String], fieldMetas:
List[FieldMeta]): ClassMeta =
apply(Identifier(), name, packageName, fieldMetas)
def apply(classMeta: ClassMeta): ClassMeta =
apply(classMeta.identifier, classMeta.name, classMeta.packageName,
classMeta.fieldMetas)
def unapply(classMeta: ClassMeta) =
Some(classMeta.identifier, classMeta.name, classMeta.packageName,
classMeta.fieldMetas)
}

56. FieldMeta VO & VO Factory
case class FieldMeta(@BeanProperty name:
String, @BeanProperty typeName: String)

57. ClassMetaRepository
package codegen.domain
class ClassMetaRepository(configSource: BufferedSource)
extends EntityResolver[ClassMeta] {
private val classMetas = new
ModelParser().parse(configSource)
private val classMetaMap = classMetas.map(classMeta =>
(classMeta.identifier, classMeta)).toMap
def iterator: Iterator[ClassMeta] =
classMetaMap.map(classMeta => ClassMeta(_._2)).iterator
def resolve(identifier: Identifier): ClassMeta =
ClassMeta(classMetaMap(identifier))
}

58. CodeGenSer vice
package codegen.domain val exportClassDir =
getExportClassDir(classMeta)
object CodeGenSer vice{
exportClassDir.mkdirs
def generate(exportDir: File, templateDir: File,
classMetas: List[ClassMeta], using(new FileWriter(new
File(exportClassDir, classMeta.name + ".java"))) {
beginHandler: Option[(ClassMeta) => Unit],
fileWriter =>
endHandler: Option[(ClassMeta) => Unit] ) = {
template.process(rootMap.asJava,
val configuration = new Configuration fileWriter);
fileWriter.flush();
configuration.setDirectoryForTemplateLoading(te
mplateDir) } / using
/
val template = / ...
/
configuration.getTemplate("java.ftl")
} / foreach
/
classMetas.foreach {
}
classMeta =>
/ ...
/
/ ...
/
}
val rootMap = Map("classMeta" ->
classMeta)

59. Application
package codegen.application getExportDir(parameters),
object Application extends Logging { getIdList(parameters))
def main(args: Array[String]) { }
try {
val commandLine = new } catch {
CommandLineParser().parse(args.mkSt
ring(" ")) case e:
CommandLineParseException =>
commandLine match { println("
case Help() => println("""-c ")
[[id1,id2]@]file.config [-t templateDir]
[-e exportDir]""") }
case parameters: Parameters => }
generate(getConfigFile(parameters),
getTemplateDir(parameters), }

60. Application
private def generate(configFile: File, CodeGenSer vice.generate(exportDir, templateDir,
targets,
templateDir: File,
Some({
exportDir: File,
c => info("id(%s) : class %s
ids: List[String]) {
".format(c.identifier.value, c.name))
info("
= %s, = %s, }),
= %s".format(configFile, templateDir, Some({
exportDir)) c => info("id(%s) : class %s
val repos = new ".format(c.identifier.value, c.name))
ClassMetaRepository(Source.fromFile(configFile))
}))
val targets = ids match {
info(" ")
case Nil => repos.toList
case xs => xs.map { } catch {
e => repos.resolve(Identifier(e)) case e: Exception => error("
} ", e)
} }
try { }