Add examples in "Lists" and other rewrites/fixes

Author: BruceEckel

Examples/CreatingGenerics/Disposable.kt

@@ -10,25 +10,25 @@ interface Disposable {
 
 class Compost(override val name: String) :
   Disposable {
-  override fun action() = "Add to composter"
-}
+    override fun action() = "Add to composter"
+  }
 
 interface Transport : Disposable
 
 class Donation(override val name: String) :
   Transport {
-  override fun action() = "Call for pickup"
-}
+    override fun action() = "Call for pickup"
+  }
 
 class Recyclable(override val name: String) :
   Transport {
-  override fun action() = "Put in bin"
-}
+    override fun action() = "Put in bin"
+  }
 
 class Landfill(override val name: String) :
   Transport {
-  override fun action() = "Put in dumpster"
-}
+    override fun action() = "Put in dumpster"
+  }
 
 val items = listOf(
   Compost("Orange Peel"),

Examples/Lists/ApparentlyMutableList.kt

@@ -0,0 +1,9 @@
+// Lists/ApparentlyMutableList.kt
+// (c)2021 Mindview LLC. See Copyright.txt for permissions.
+import atomictest.eq
+
+fun main() {
+  var list = listOf('X') // Immutable
+  list += 'Y' // Appears to be mutable
+  list eq "[X, Y]"
+}

Examples/Lists/MultipleListRefs.kt

@@ -6,8 +6,7 @@ fun main() {
   val first = mutableListOf(1)
   val second: List<Int> = first
   second eq listOf(1)
-
-  first += 2
+  first.add(2)
   // second sees the change:
   second eq listOf(1, 2)
 }

Examples/Lists/MutListIsList.kt

@@ -3,13 +3,12 @@
 package lists
 import atomictest.eq
 
-fun getList(): List<Int> {
-  return mutableListOf(1, 2, 3)
-}
+fun makeList(): List<Int> =
+  mutableListOf(1, 2, 3)
 
 fun main() {
-  // getList() produces a read-only List:
-  val list = getList()
-  // list += 3 // Error
+  // makeList() produces a read-only List:
+  val list = makeList()
+  // list.add(3) // Unresolved reference: add
   list eq listOf(1, 2, 3)
 }

Examples/Lists/PlusAssignPuzzle.kt

@@ -0,0 +1,25 @@
+// Lists/PlusAssignPuzzle.kt
+// (c)2021 Mindview LLC. See Copyright.txt for permissions.
+import atomictest.eq
+
+fun main() {
+    // Mutable List assigned to a 'val'/'var':
+    val list1 = mutableListOf('A') // or 'var'
+    list1 += 'A' // Is the same as:
+    list1.plusAssign('A')               // [1]
+
+    // Immutable List assigned to a 'val':
+    val list2 = listOf('B')
+    // list2 += 'B' // Is the same as:
+    // list2 = list2 + 'B'              // [2]
+
+    // Immutable List assigned to a 'var':
+    var list3 = listOf('C')
+    list3 += 'C' // Is the same as:
+    val newList = list3 + 'C'           // [3]
+    list3 = newList                     // [4]
+
+    list1 eq "[A, A, A]"
+    list2 eq "[B]"
+    list3 eq "[C, C, C]"
+}

README.md

@@ -385,7 +385,7 @@ on the Mac, "Extract Here" on Linux, or "Extract all ..." on Windows.
 # Appendix B: Command-Line Hello World
 
 This appendix explains how to compile and run the program shown in the "Hello
-World" atom in the book, using the latest version (1.4 or higher) of the
+World" atom in the book, using the latest version (1.5 or higher) of the
 [Kotlin command-line compiler](http://kotlinlang.org/docs/tutorials/command-line.html).
 
 Open up a console window in the `HelloWorld` directory, where you'll see
@@ -455,15 +455,15 @@ kotlin bar.FooKt
 
 The Kotlin interpreter is also called the REPL (for *Read-Evaluate-Print-
 Loop*). To use this you must first install the
-latest version (1.4 or higher) of the [Kotlin command-line
+latest version (1.5 or higher) of the [Kotlin command-line
 compiler](http://kotlinlang.org/docs/tutorials/command-line.html).
 
 > NOTE: You do not need to install command-line Kotlin for the operations
 > described previously in this README.
 
 ## Install Kotlin
 
-In this book, we use Kotlin version 1.4, the latest available at the time. The
+In this book, we use Kotlin version 1.5, the latest available at the time. The
 detailed installation instructions for the command-line compiler are available
 at [The Kotlin Site](https://kotlinlang.org/docs/tutorials/command-line.html).
 
@@ -482,13 +482,13 @@ To start the REPL, type `kotlinc` by itself on the command line. You should see
 something like the following:
 
 ```
-Welcome to Kotlin version 1.4 (JRE 1.8.0_144-b01)
+Welcome to Kotlin version 1.5 (JRE 1.8.0_144-b01)
 Type :help for help, :quit for quit
 >>>
 ```
 
 The exact version numbers will vary depending on the versions of Kotlin
-and Java you've installed, but make sure that you're running Kotlin 1.4
+and Java you've installed, but make sure that you're running Kotlin 1.5
 or greater.
 
 The REPL gives you immediate interactive feedback, which is helpful for

Tests/TestExamples.java

@@ -1822,6 +1822,11 @@ public void testPropertyOptions() {
     testExample("Examples/LazyInitialization/PropertyOptions.kt", lazyinitialization.PropertyOptionsKt::main);
   }
 
+  @Test
+  public void testApparentlyMutableList() {
+    testExample("Examples/Lists/ApparentlyMutableList.kt", ApparentlyMutableListKt::main);
+  }
+
   @Test
   public void testLists() {
     testExample("Examples/Lists/Lists.kt", ListsKt::main);
@@ -1862,6 +1867,11 @@ public void testParameterizedTypes() {
     testExample("Examples/Lists/ParameterizedTypes.kt", ParameterizedTypesKt::main);
   }
 
+  @Test
+  public void testPlusAssignPuzzle() {
+    testExample("Examples/Lists/PlusAssignPuzzle.kt", PlusAssignPuzzleKt::main);
+  }
+
   @Test
   public void testTask127() {
     testExample("Examples/Lists/Task1.kt", listsExercise1.Task1Kt::main);

gradle/tasks.gradle

@@ -85,6 +85,11 @@ task AnyInstead(type: JavaExec) {
     main = 'introgenerics.AnyInsteadKt'
 }
 
+task ApparentlyMutableList(type: JavaExec) {
+    classpath kotlinClassPath
+    main = 'ApparentlyMutableListKt'
+}
+
 task Arg(type: JavaExec) {
     classpath kotlinClassPath
     main = 'ArgKt'
@@ -2125,6 +2130,11 @@ task PlayingCards(type: JavaExec) {
     main = 'manipulatinglists.PlayingCardsKt'
 }
 
+task PlusAssignPuzzle(type: JavaExec) {
+    classpath kotlinClassPath
+    main = 'PlusAssignPuzzleKt'
+}
+
 task Postconditions(type: JavaExec) {
     classpath kotlinClassPath
     main = 'checkinstructions.PostconditionsKt'
@@ -3058,6 +3068,7 @@ task run (dependsOn: [
     'Any',
     'AnyFromListOfStar',
     'AnyInstead',
+    'ApparentlyMutableList',
     'Arg',
     'ArgumentOrder',
     'ArithmeticOperators',
@@ -3466,6 +3477,7 @@ task run (dependsOn: [
     'PlatformTypes',
     'PlayerInterface',
     'PlayingCards',
+    'PlusAssignPuzzle',
     'Postconditions',
     'PostfixVsPrefix',
     'Predicates',