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| // | |
| // https://twitter.com/yanzm/status/1096312798412328970 | |
| // | |
| //「3の倍数のときは fizz が返る」 | |
| //「5の倍数のときは buzz が返る」 | |
| //「3の倍数かつ5の倍数のときは fizzbuzz が返る」 | |
| //「3の倍数でも5の倍数でもないときはそのままの数字が返る」 | |
| // は | |
| // ① Entity または ValueObject（Clean Architecture だと Entities に入る）がもつロジックだと思う | |
| // ② DomainService （これも Clean Architecture だと Entities に入る）だと思う | |
| // ③ UseCase （DDD だと ApplicationService）だと思う | |
| // ④ UseCase （DDD だと ApplicationService）だと思う 2 | |
| // | |
| // ① Entity または ValueObject（Clean Architecture だと Entities に入る）がもつロジックだと思う | |
| // | |
| // at domain | |
| // | |
| data class FizzBuzz(private val number: Int) { | |
| fun expression(): String { | |
| val isMul3 = number % 3 == 0 | |
| val isMul5 = number % 5 == 0 | |
| return when { | |
| isMul3 && isMul5 -> "fizzbuzz" | |
| isMul3 -> "fizz" | |
| isMul5 -> "buzz" | |
| else -> number.toString() | |
| } | |
| } | |
| } | |
| // | |
| // ② DomainService （これも Clean Architecture だと Entities に入る）だと思う | |
| // ③ UseCase （DDD だと ApplicationService）だと思う | |
| // ④ UseCase （DDD だと ApplicationService）だと思う 2 | |
| // | |
| // at domain layer | |
| // | |
| class FizzBuzzNumber(private val number: Int) { | |
| val isMul3 = number % 3 == 0 | |
| val isMul5 = number % 5 == 0 | |
| override fun toString(): String { | |
| return number.toString() | |
| } | |
| } | |
| // | |
| // ② DomainService （これも Clean Architecture だと Entities に入る）だと思う | |
| // | |
| // at domain layer | |
| // | |
| class FizzBuzzService { | |
| fun expression(number: FizzBuzzNumber): String { | |
| return when { | |
| number.isMul3 && number.isMul5 -> "fizzbuzz" | |
| number.isMul3 -> "fizz" | |
| number.isMul5 -> "buzz" | |
| else -> number.toString() | |
| } | |
| } | |
| } | |
| // | |
| // ③ UseCase （DDD だと ApplicationService）だと思う | |
| // | |
| // at application layer | |
| // | |
| class FizzBuzzUseCase { | |
| fun expression(number: FizzBuzzNumber): String { | |
| return when { | |
| number.isMul3 && number.isMul5 -> "fizzbuzz" | |
| number.isMul3 -> "fizz" | |
| number.isMul5 -> "buzz" | |
| else -> number.toString() | |
| } | |
| } | |
| } | |
| // | |
| // ④ UseCase （DDD だと ApplicationService）だと思う 2 | |
| // | |
| // | |
| // at domain layer | |
| // | |
| sealed class FizzBuzzState { | |
| abstract val expression: String | |
| } | |
| object Fizz : FizzBuzzState() { | |
| override val expression: String = "fizz" | |
| } | |
| object Buzz : FizzBuzzState() { | |
| override val expression: String = "buzz" | |
| } | |
| object FizzBuzz : FizzBuzzState() { | |
| override val expression: String = "fizzbuzz" | |
| } | |
| data class Normal(private val number: Int) : FizzBuzzState() { | |
| override val expression: String = number.toString() | |
| } | |
| // | |
| // at application layer | |
| // | |
| class FizzBuzzUseCase { | |
| fun expression(number: Int): FizzBuzzState { | |
| val isMul3 = number % 3 == 0 | |
| val isMul5 = number % 5 == 0 | |
| return when { | |
| isMul3 && isMul5 -> FizzBuzz | |
| isMul3 -> Fizz | |
| isMul5 -> Buzz | |
| else -> Normal(number) | |
| } | |
| } | |
| } | |
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