patrickcousins

package com.example.android.lib.rx

import io.reactivex.Observable
import java.util.concurrent.ConcurrentLinkedDeque
import java.util.concurrent.TimeUnit

class JobExample {

    val queue = ConcurrentLinkedDeque<Item>()

patrickcousins

import kotlin.reflect.KClass

sealed class States {
    sealed class StateA : States() {
        object One : StateA()
        object Two : StateA()
    }

    sealed class StateB : States() {
        object Three : StateB()

patrickcousins

fun isRich(person: Person) : Boolean {
    causeSideEffect()
    readInternalState()
    return unexpectedValue
}

patrickcousins

fun calculateDiscount(person: Person) : Int  {
    return when {
        over65(person) -> 20
        under13(person) -> 10
        isRich(person) -> 0
        else -> 5
    }
}

patrickcousins

private fun over65(person: Person) : Boolean {
    return person.age > 65
}
private fun under13(person: Person): Boolean {
    return person.age < 13
}
private fun isRich(person: Person) : Boolean {
    return person.income > 100_000
}

patrickcousins

//all the code below is in the file DiscountCalculator.kt

class DiscountCalculator {
    //...
}

private fun Person.over65() : Boolean {
    return this.age > 65
}

patrickcousins

@Test
fun over65() {
    val person = Person("test", 70)
    assertTrue(person.over65())
}

patrickcousins

fun calculateDiscount(person: Person) : Int  {
    return when {
        person.over65() -> 20
        person.under13() -> 10
        person.isRich() -> 0
        else -> 5
    }
}

patrickcousins

class Person(private val name: String, val age: Int, val income: Int = 0) {

    fun over65(): Boolean {
        return age > 65
    }

    fun under13(): Boolean {
        return age < 13
    }

patrickcousins

fun calculateDiscount(person: Person) : Int {
    return when {
        person.age > 65 -> 20
        person.age < 13 -> 10
        person.income > 1_000_000 -> 0
        else -> 5
    }
}