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4DBMBͰͭ͘Δ
*OWBMJETUBUFͷͳ͍ੈք
:"1$"TJB)BDIJPKJNJEJO4IJOBHBXBTUEBZ
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ࣗݾհ
ͨͬ͘ΜʢUBLLLVOʣ
ͲͷαʔϏεͰେମ͜ͷ໊લ
4DBMB
3VCZ
&SMBOH
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ࠓճԿͷʁ
4DBMBͰͭ͘Δ
*OWBMJETUBUFͷͳ͍ੈք
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ࠓճԿͷʁ
4DBMBͰͭ͘Δ
*OWBMJETUBUFͷͳ͍ੈք
ˣ
όϦσʔγϣϯͷ͓
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ࠓճԿͷʁ
4DBMBͰͭ͘Δ
*OWBMJETUBUFͷͳ͍ੈք
ˣ
όϦσʔγϣϯͷ͓
όϦσʔγϣϯʹࣦഊͨ͠ঢ়ଶΛࢦ͢
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ൃදʹࢸͬͨܦҢ
w ීஈ4DBMBͰΞϓϦέʔγϣϯΞʔΩςΫνϟ͔
Βݕ౼ͭͭ͠։ൃ
w ΦϒδΣΫτͷόϦσʔγϣϯʹؔͯ݁͠ߏ಄
Λ೧Δ͜ͱ͕͋ͬͨ
w ࢼߦࡨޡ͍ͯͨ͠Βྑ͍ײ͡ͷ͕ग़དྷͨ
w ࣌ʮϠύνʔΔͧʂʯͱ͍͏
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ͳΒͦ͏ʂ
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ΦϒδΣΫτΛόϦσʔγϣϯ͢Δ
w ͱ͋ΔΦϒδΣΫτ͕͋Δ
w ͦͷΦϒδΣΫτͻͱͭͳ͍͠ෳͷϑΟʔ
ϧυΛ࣋ͭ
w ͦͷϑΟʔϧυͷ༰ԿͰΦϒδΣΫτࣗମ
ͷ༗ޮແޮΛܾఆ͢Δ
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class Person < ActiveRecord::Base
validates :name, {
presence: true
}
validates :age, {
presence: true,
numericality: {greater_than_or_equal_to: 0}
}
end
person = Person.new(name: "takkkun", age: -1)
if (person.invalid?) {
# handle person.errors
}
ΦϒδΣΫτΛόϦσʔγϣϯ͢Δ
"DUJWF3FDPSEͷྫ
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ΦϒδΣΫτΛόϦσʔγϣϯ͢Δ
4DBMBͷྫ
class Person(val name: String, val age: Int) {
def validate(): List[String] = {
var errors: List[String] = List.empty
if (name.isEmpty) {
errors :+= "name cannot be blank"
}
if (age < 0) {
errors :+= "age must be zero or a positive number"
}
errors
}
def isValid(): Boolean = validate().isEmpty
}
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ѻ͏ଆ͕όϦσʔγϣϯ࣮ߦͷΛ࣋ͭ
val person = new Person("takkkun", -1)
if (!person.isValid) {
val errors = person.validate()
// handle errors
}
ѻ͏ଆ͕όϦσʔγϣϯΛݺͼग़͠ɺؾʹ͔͚Δඞཁ͕͋Δ
val person = new Person("takkkun", -1)
// handle person όϦσʔγϣϯΛݺͼग़͞ͳ͍ϛεى͜ΓಘΔ
def handlePerson(person: Person) {
if (person.isValid) {
// handle person
}
}
ؔͳͲͰڥքΛ·͍ͨͩ߹ؾʹ͔͚Δඞཁ͕͋Δ
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ΊΜͲ͍͘͞ʂ
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w ͜ͷΞϓϩʔνʮΦϒδΣΫτ͕༗ޮແޮͱ
͍͏ঢ়ଶʯΛ࣋ͭ
w ঢ়ଶΛ࣋ͭҎ্ؾʹ͔͚Δඞཁ͕͋Δ
w ·ͨɺ༗ޮແޮҎ֎ʹঢ়ଶΛ࣋ͭ͜ͱߟ͑
ΒΕΔ
w ͍ΖΜͳঢ়ଶ͕Έ߹Θ͞Δͱʜʜ
ʮঢ়ଶʯةݥͳݴ༿
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ΊΜͲ͍͘͞ʂʂ
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ʮৗʹ༗ޮʯͱ͍͏ߟ͑ํ
w ʮΦϒδΣΫτ͕༗ޮແޮͰ͋Δͱ͍͏ঢ়ଶʯ
͕अຐͳΒແͯ͘͠͠·͓͏
w ͢ͳΘͪʮৗʹ༗ޮʯ
w ͜ͷΞϓϩʔνࣗମ͍͠Θ͚Ͱͳ͍
ʢྫ࣌ΫϥεͳͲʣ
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ʮৗʹ༗ޮʯͱ͍͏ߟ͑ํ
w %%%ͷจ຺ʹ͓͚ΔΤϯςΟςΟͰɺʮৗʹ༗
ޮͳΤϯςΟςΟʯͱͯ͠l"MXBZTWBMJEFOUJUZz
ͱ͍͏ݴ༿͕ΘΕ͍ͯΔ
w ͦΕʹͳΒ͍ʮৗʹ༗ޮʯl"MXBZTWBMJEzͱশ
͢Δ
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"MXBZTWBMJE*OWBMJETUBUF͕ͳ͍
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4DBMBͰͭ͘Δ
*OWBMJETUBUFͷͳ͍ੈք
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ͪͳΈʹ
"MXBZTWBMJEΛ൷͢Δߟ͑ํ͋Δ
IUUQKF⒎SFZQBMFSNPDPNCMPHUIFGBMMBDZPG
UIFBMXBZTWBMJEFOUJUZ
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class Person(val name: String, val age: Int) {
var errors: List[String] = List.empty
if (name.isEmpty) {
errors :+= "name cannot be blank"
}
if (age < 0) {
errors :+= "age must be zero or a positive number"
}
if (errors.nonEmpty) {
throw new Exception(errors.mkString(", "))
}
}
4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δ
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class Person(val name: String, val age: Int) {
var errors: List[String] = List.empty
if (name.isEmpty) {
errors :+= "name cannot be blank"
}
if (age < 0) {
errors :+= "age must be zero or a positive number"
}
if (errors.nonEmpty) {
throw new Exception(errors.mkString(", "))
}
}
4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δ
όϦσʔγϣϯʹࣦഊͨ͠ͱ͖ྫ֎ͱ͢Δ
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"MXBZTWBMJEຬ͍ͨͤͯΔ͕ʜʜ
w ίϯετϥΫλͰࣄ্࣮ྫ֎ͰࣦഊΛΒͤ
Δ͔͠ͳ͍ͷͰɺऔΓճ͕͠ޮ͔ͳ͍ʢҰԠ
TDBMBVUJM5SZͰͳΜͱ͔ग़དྷΔʣ
w όϦσʔγϣϯΛॻ͔ͳ͍ϛε͛ͳ͍ʢς
ετॻ͜͏Ͷʣ
w ͳΜͱ͔ͳΔ͕ɺͳΜ͔ͩΜͩ৽ͨͳ͕
ු্ͯ͘͠Δ
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4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
class Person private (val name: String, val age: Int)
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Person = {
// ...
}
}
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4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
class Person private (val name: String, val age: Int)
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Person = {
// ...
}
}
ίϯετϥΫλΛQSJWBUFʹ͢ΔʢΫϥεࣗମQVCMJDʣ
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4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
class Person private (val name: String, val age: Int)
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Person = {
// ...
}
}
TQBXOϝιουܦ༝ͰͷΈ1FSTPOΫϥεͷΠϯελϯεΛੜՄೳ
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4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
class Person private (val name: String, val age: Int)
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Person = {
// ...
}
}
ܕΛม͑ͯͤͳ͍Α͏ʹ͢Δ
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class Indefinite[A](value: A) {
def validateWith(validateValue: A => List[String]): Validity[A] = {
val errors = validateValue(value)
if (errors.isEmpty) Valid(value) else Invalid(errors)
}
}
sealed trait Validity[+A] {
def value: A
def errors: List[String]
}
case class Valid[A](value: A) extends Validity[A] {
val errors = List.empty
}
case class Invalid(errors: List[String]) extends Validity[Nothing] {
def value = throw new NoSuchElementException("Invalid")
}
4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
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class Indefinite[A](value: A) {
def validateWith(validateValue: A => List[String]): Validity[A] = {
val errors = validateValue(value)
if (errors.isEmpty) Valid(value) else Invalid(errors)
}
}
sealed trait Validity[+A] {
def value: A
def errors: List[String]
}
case class Valid[A](value: A) extends Validity[A] {
val errors = List.empty
}
case class Invalid(errors: List[String]) extends Validity[Nothing] {
def value = throw new NoSuchElementException("Invalid")
}
ҙͷܕʢ"ʣͷΛऔΔɻWBMͰम০͍ͯ͠ͳ͍ͷͰɺ֎෦ʹެ։͞Εͳ͍
4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
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class Indefinite[A](value: A) {
def validateWith(validateValue: A => List[String]): Validity[A] = {
val errors = validateValue(value)
if (errors.isEmpty) Valid(value) else Invalid(errors)
}
}
sealed trait Validity[+A] {
def value: A
def errors: List[String]
}
case class Valid[A](value: A) extends Validity[A] {
val errors = List.empty
}
case class Invalid(errors: List[String]) extends Validity[Nothing] {
def value = throw new NoSuchElementException("Invalid")
}
WBMJEBUF8JUIϝιουͰแ͍ͯ͠Δͷ༗ޮແޮΛ͔֬ΊΔ
4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
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4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
class Person private (val name: String, val age: Int)
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Person = {
(name.validateWith(validateName), age.validateWith(validateAge)) match {
case (Valid(validName), Valid(validAge)) =>
new Person(validName, validAge)
case (validityName, validityAge) =>
throw new Exception((validityName.errors ++ validityAge.errors).mkString(", "))
}
}
private def validateName(name: String): List[String] = {
if (name.isEmpty) List("name cannot be blank") else List.empty
}
private def validateAge(age: Int): List[String] = {
if (age < 0) List("age must be zero or a positive number") else List.empty
}
}
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4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
class Person private (val name: String, val age: Int)
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Person = {
(name.validateWith(validateName), age.validateWith(validateAge)) match {
case (Valid(validName), Valid(validAge)) =>
new Person(validName, validAge)
case (validityName, validityAge) =>
throw new Exception((validityName.errors ++ validityAge.errors).mkString(", "))
}
}
private def validateName(name: String): List[String] = {
if (name.isEmpty) List("name cannot be blank") else List.empty
}
private def validateAge(age: Int): List[String] = {
if (age < 0) List("age must be zero or a positive number") else List.empty
}
}
WBMJEBUF8JUIʹόϦσʔγϣϯ༻ͷؔΛ
͠ɺแ͞Ε͍ͯΔͷ༗ޮແޮΛಘΔ
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4DBMBͰ"MXBZTWBMJEΛ࣮ݱ͢Δվ
class Person private (val name: String, val age: Int)
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Person = {
(name.validateWith(validateName), age.validateWith(validateAge)) match {
case (Valid(validName), Valid(validAge)) =>
new Person(validName, validAge)
case (validityName, validityAge) =>
throw new Exception((validityName.errors ++ validityAge.errors).mkString(", "))
}
}
private def validateName(name: String): List[String] = {
if (name.isEmpty) List("name cannot be blank") else List.empty
}
private def validateAge(age: Int): List[String] = {
if (age < 0) List("age must be zero or a positive number") else List.empty
}
}
ύλʔϯϚονͰͯ͢༗ޮͷͱ͖ͷΈ1FSTPOΫϥεͷΠϯελϯεΛੜ͢Δ
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༻ྫ
try {
val name = new Indefinite("takkkun")
val age = new Indefinite(-1)
val person = Person.spawn(name, age)
// handle person
} catch {
case e: Exception =>
// handle exception
}
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&JUIFSόʔδϣϯ
object Person {
def spawn(name: Indefinite[String], age: Indefinite[Int]): Either[List[String], Person] = {
(name.validateWith(validateName), age.validateWith(validateAge)) match {
case (Valid(validName), Valid(validAge)) =>
Right(new Person(validName, validAge))
case (validityName, validityAge) =>
Left(validityName.errors ++ validityAge.errors)
}
}
// ...
}
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&JUIFSόʔδϣϯ༻ྫ
val name = new Indefinite("takkkun")
val age = new Indefinite(-1)
val errorsOrPerson = Person.spawn(name, age)
errorsOrPerson match {
case Left(errors) =>
// handle errors
case Right(person) =>
// handle person
}
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·ͱΊ
w ʮΦϒδΣΫτ͕༗ޮ͔ແޮ͔ͱ͍͏ঢ়ଶʯΛ
࣋ͭͷ໘͞૿େͷஹީ
w ނʹΦϒδΣΫτৗʹ༗ޮʢ"MXBZTWBMJEʣͰ
͋Εɺͱ͍͏ߟ͑ํ
w 4DBMBͳͲͷ੩తܕ͚ݴޠͰ͋ΕɺܕͰόϦ
σʔγϣϯʹڧ੍ྗΛ࣋ͨͤΒΕΔ
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ϦϥΫͰ։ൃऀΛืू͍ͯ͠·͢
w ීஈ͜͏͍͏͜ͱΛߟ͑ͳ͕Β։ൃ͍ͯ͠·͢
w αʔόʔαΠυ4DBMB͕ओ
w J04 4XJGU
"OESPJE
w Δ͜ͱ͍ͬͺ͍͋Δ
w ڵຯ͕͋Δํ!UBLLLVO·Ͱ
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͓͠·͍