Regenerated samples

Power Tools/Creating Generics/Examples/src/CheckType.kt

@@ -3,6 +3,7 @@ package creatinggenerics
 import atomictest.eq
 
 inline fun <reified T> check(t: Any) = t is T
+// fun <T> check1(t: Any) = t is T      // [1]
 
 fun main() {
   check<String>("1") eq true

Power Tools/Creating Generics/Examples/src/Constraints.kt

@@ -4,8 +4,8 @@ import kotlin.random.Random
 
 private val rnd = Random(47)
 
-// Accesses action() but can't return
-// the exact type:
+// Accesses action() but can't
+// return the exact type:
 fun List<Disposable>.inexact(): Disposable {
   val d: Disposable = this[rnd.nextInt(size)]
   d.action()

Power Tools/Creating Generics/Examples/src/DefiningGenerics.kt

@@ -22,6 +22,13 @@ class GImplementation<T>(
   override fun f(): T = x
 }
 
+class ConcreteImplementation
+  : GInterface<String> {
+  override val x: String
+    get() = "x"
+  override fun f() = "f()"
+}
+
 fun basicGenerics() {
   gFunction("Yellow")
   gFunction(1)
@@ -41,4 +48,7 @@ fun basicGenerics() {
   GImplementation("Cyan").f()
   GImplementation(11).f()
   GImplementation(Dog()).f().bark()
+
+  ConcreteImplementation().f()
+  ConcreteImplementation().x
 }

Power Tools/Creating Generics/Examples/src/Erasure.kt

@@ -0,0 +1,17 @@
+// CreatingGenerics/Erasure.kt
+package creatinggenerics
+
+fun main() {
+  val strings = listOf("a", "b", "c")
+  val all: List<Any> = listOf(1, 2, "x")
+  useList(strings)
+  useList(all)
+}
+
+fun useList(list: List<Any>) {
+  // Doesn't compile:
+  /*
+  if (list is List<String>) {   // [1]
+  }
+  */
+}

Power Tools/Creating Generics/Examples/src/ReificationA.kt

@@ -1,6 +1,7 @@
 // CreatingGenerics/ReificationA.kt
 package creatinggenerics
+import kotlin.reflect.KClass
 
-fun <T> a(class_: Class<T>) {
-  // Uses Class<T>
+fun <T: Any> a(kClass: KClass<T>) {
+  // Uses KClass<T>
 }

Power Tools/Creating Generics/Examples/src/ReificationB.kt

@@ -2,4 +2,4 @@
 package creatinggenerics
 
 // Doesn't compile because of erasure:
-// fun <T> b() = a(T::class.java)
+// fun <T: Any> b() = a(T::class)

Power Tools/Creating Generics/Examples/src/ReificationC.kt

@@ -1,8 +1,9 @@
 // CreatingGenerics/ReificationC.kt
 package creatinggenerics
+import kotlin.reflect.KClass
 
-fun <T> c(class_: Class<T>) = a(class_)
+fun <T: Any> c(kClass: KClass<T>) = a(kClass)
 
 class K
 
-val kc = c(K::class.java)
+val kc = c(K::class)

Power Tools/Creating Generics/Examples/src/ReificationD.kt

@@ -1,6 +1,6 @@
 // CreatingGenerics/ReificationD.kt
 package creatinggenerics
 
-inline fun <reified T> d() = a(T::class.java)
+inline fun <reified T: Any> d() = a(T::class)
 
 val kd = d<K>()

Power Tools/Creating Generics/Examples/task-info.yaml

@@ -20,6 +20,8 @@ files:
   visible: true
 - name: src/Constraints.kt
   visible: true
+- name: src/Erasure.kt
+  visible: true
 - name: src/ReificationA.kt
   visible: true
 - name: src/ReificationB.kt

Preventing Failure/Exception Handling/Examples/src/CaptureImplementation.kt

@@ -1,20 +1,23 @@
 // ExceptionHandling/CaptureImplementation.kt
 package exceptionhandling
-import atomictest.eq
+import atomictest.CapturedException
 
-fun capture(f: () -> Unit): String =  // [1]
-  try {                               // [2]
+fun capture(f:() -> Unit): CapturedException =
+  try {                                 // [1]
     f()
-    "Error: Expected an exception"    // [3]
-  } catch (e: Throwable) {            // [4]
-    "${e::class.simpleName}: ${e.message}"
+    CapturedException(null,             // [2]
+      "<Error>: Expected an exception")
+  } catch (e: Throwable) {              // [3]
+    CapturedException(e::class,         // [4]
+      if (e.message != null) ": ${e.message}"
+      else "")
   }
 
 fun main() {
   capture {
     throw Exception("!!!")
-  } eq "Exception: !!!"
+  } eq "Exception: !!!"                 // [5]
   capture {
     1
-  } eq "Error: Expected an exception"
+  } eq "<Error>: Expected an exception"
 }

Preventing Failure/Resource Cleanup/Exercise 1/task.md

@@ -6,7 +6,7 @@ function that uses `java.io.File`. Create a `File` object initialized to
 and add `text` to the file (IntelliJ IDEA will give you hints to help choose
 the member functions to call for `File`). Use `useLines()` to read the file and
 display it with `println()`, then use `forEachLine()` to read the file and
-display it with `println()`. The starter code in `main()` 
+display it with `println()`. The starter code in `main()` tests
 `writeAndRead()`.
 
 <sub> This task doesn't contain automatic tests,

Preventing Failure/The Nothing Type/Examples/src/ListOfNothing.kt

@@ -1,6 +1,18 @@
 // NothingType/ListOfNothing.kt
+import atomictest.eq
 
 fun main() {
   val none: Nothing? = null
+
+  var nullableString: String? = null    // [1]
+  nullableString = "abc"
+  nullableString = none                 // [2]
+  nullableString eq null
+
+  val nullableInt: Int? = none          // [3]
+  nullableInt eq null
+
   val listNone: List<Nothing?> = listOf(null)
+  val ints: List<Int?> = listOf(null)   // [4]
+  ints eq listNone
 }

util/test/TestAllExamples.java

@@ -2301,6 +2301,11 @@ public class TestAllExamples extends AbstractTestExamples {
         testExample("Power Tools/Creating Generics/Examples/src/Select.kt", creatinggenerics.SelectKt::main);
     }
 
+    @Test
+    public void testErasure() {
+        testExample("Power Tools/Creating Generics/Examples/src/Erasure.kt", creatinggenerics.ErasureKt::main);
+    }
+
     @Test
     public void testCarCrate() {
         testExample("Power Tools/Creating Generics/Examples/src/CarCrate.kt", creatinggenerics.CarCrateKt::main);