дз №2

src/main/kotlin/ru/otus/homework/Builder.kt

@@ -0,0 +1,26 @@
+package ru.otus.homework
+
+class Car(
+    val model: String?,
+    val color: String?,
+    val type: String?) {
+
+    data class Builder(
+        var model: String? = null,
+        var color: String? = null,
+        var type: String? = null) {
+
+        fun model(model: String) = apply { this.model = model }
+        fun color(color: String) = apply { this.color = color }
+        fun type(type: String) = apply { this.type = type }
+        fun build() = Car(model, color, type)
+    }
+}
+
+fun main() {
+    val car = Car.Builder()
+        .model("Ford Focus")
+        .color("Black")
+        .type("Type")
+        .build()
+}

src/main/kotlin/ru/otus/homework/Command.kt

@@ -0,0 +1,37 @@
+package ru.otus.homework
+
+interface OrderCommand {
+    fun execute()
+}
+
+class OrderAddCommand(private val id: Long) : OrderCommand {
+    override fun execute() = println("Adding order with id: $id")
+}
+
+class OrderPayCommand(private val id: Long) : OrderCommand {
+    override fun execute() = println("Paying for order with id: $id")
+}
+
+class CommandProcessor {
+
+    private val queue = ArrayList<OrderCommand>()
+    fun addToQueue(orderCommand: OrderCommand): CommandProcessor =
+        apply {
+            queue.add(orderCommand)
+        }
+
+    fun processCommands(): CommandProcessor =
+        apply {
+            queue.forEach { it.execute() }
+            queue.clear()
+        }
+}
+
+fun main() {
+        CommandProcessor()
+        .addToQueue(OrderAddCommand(1L))
+        .addToQueue(OrderAddCommand(2L))
+        .addToQueue(OrderPayCommand(2L))
+        .addToQueue(OrderPayCommand(1L))
+        .processCommands()
+  }

src/main/kotlin/ru/otus/homework/Decorator.kt

@@ -0,0 +1,58 @@
+package ru.otus.homework
+
+interface ChristmasTree {
+    fun decorate(): String
+}
+
+class PineChristmasTree : ChristmasTree {
+
+    override fun decorate() = "Christmas tree"
+}
+
+abstract class TreeDecorator
+    (private val tree: ChristmasTree) : ChristmasTree {
+
+    override fun decorate(): String {
+        return tree.decorate()
+    }
+}
+
+class BubbleLights(tree: ChristmasTree) : TreeDecorator(tree) {
+    override fun decorate(): String {
+        return super.decorate() + decorateWithBubbleLights()
+    }
+
+    private fun decorateWithBubbleLights(): String {
+        return " with Bubble Lights"
+    }
+}
+
+fun christmasTreeWithBubbleLights() {
+
+    val christmasTree = BubbleLights(PineChristmasTree())
+    val decoratedChristmasTree = christmasTree.decorate()
+    println(decoratedChristmasTree)
+}
+
+fun christmasTreeWithGarlands() {
+
+    val christmasTree = Garlands(PineChristmasTree())
+    val decoratedChristmasTree = christmasTree.decorate()
+    println(decoratedChristmasTree)
+}
+
+class Garlands(private val tree: ChristmasTree) : ChristmasTree by tree {
+
+    override fun decorate(): String {
+        return tree.decorate() + decorateWithGarlands()
+    }
+
+    private fun decorateWithGarlands(): String {
+        return " with Garlands"
+    }
+}
+
+fun main() {
+    christmasTreeWithBubbleLights()
+    christmasTreeWithGarlands()
+}

src/main/kotlin/ru/otus/homework/Singleton.kt

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+package ru.otus.homework
+
+class Singleton private constructor() {
+
+    companion object {
+        val instance:Singleton by lazy {
+            Singleton()
+        }
+    }
+}
+
+fun main() {
+    val instance = Singleton.instance
+}