#619 ScalaExercises 2º Part

src/main/scala/scalatutorial/sections/ClassesVsCaseClasses.scala

@@ -155,7 +155,7 @@ object ClassesVsCaseClasses extends ScalaTutorialSection {
    *     }
    *
    *     // toString redefinition to return the value of an instance instead of its memory addres
-   *     override def toString = s"Note($name, $duration, $octave)"
+   *     override def toString = s"Note($name,$duration,$octave)"
    *
    *     // Create a copy of a case class, with potentially modified field values
    *     def copy(name: String = name, duration: String = duration, octave: Int = octave): Note =
@@ -170,12 +170,19 @@ object ClassesVsCaseClasses extends ScalaTutorialSection {
    *       new Note(name, duration, octave)
    *
    *     // Extractor for pattern matching
-   *     def unapply(note: Note): Option[(String, String, Int)) =
+   *     def unapply(note: Note): Option[(String, String, Int)] =
    *       if (note eq null) None
    *       else Some((note.name, note.duration, note.octave))
    *
    *   }
    * }}}
    */
-  def nothing(): Unit = ()
+  def encoding(res0: String, res1: Boolean, res2: String): Unit = {
+    val c3 = Note("C", "Quarter", 3)
+    c3.toString shouldBe res0
+    val d = Note("D", "Quarter", 3)
+    c3.equals(d) shouldBe res1
+    val c4 = c3.copy(octave = 4)
+    c4.toString shouldBe res2
+  }
 }

src/main/scala/scalatutorial/sections/LazyEvaluation.scala

@@ -209,6 +209,18 @@ object LazyEvaluation extends ScalaTutorialSection {
    *   lazy val x = expr
    * }}}
    *
+   * = Lazy Vals and Streams =
+   *
+   * Using a lazy value for `tail`, `Stream.cons` can be implemented more efficiently:
+   *
+   * {{{
+   *   def cons[T](hd: T, tl: => Stream[T]) = new Stream[T] {
+   *     def head = hd
+   *     lazy val tail = tl
+   *     …
+   *   }
+   * }}}
+   *
    * == Exercise ==
    */
   def lazyVal(res0: String): Unit = {
@@ -223,18 +235,4 @@ object LazyEvaluation extends ScalaTutorialSection {
     builder.result() shouldBe res0
   }
 
-  /**
-   * = Lazy Vals and Streams =
-   *
-   * Using a lazy value for `tail`, `Stream.cons` can be implemented more efficiently:
-   *
-   * {{{
-   *   def cons[T](hd: T, tl: => Stream[T]) = new Stream[T] {
-   *     def head = hd
-   *     lazy val tail = tl
-   *     …
-   *   }
-   * }}}
-   */
-  def nothing(): Unit = ()
 }

src/main/scala/scalatutorial/sections/StructuringInformation.scala

@@ -141,20 +141,20 @@ object StructuringInformation extends ScalaTutorialSection {
    * the possible case of symbols is fixed. The compiler can leverage this
    * knowledge to warn us if we write code that does not handle ''all''
    * the cases:
-   */
-  def unexhaustive(): Unit = {
-    sealed trait Symbol
-    case class Note(name: String, duration: String, octave: Int) extends Symbol
-    case class Rest(duration: String)                            extends Symbol
-
-    def nonExhaustiveDuration(symbol: Symbol): String =
-      symbol match {
-        case Rest(duration) => duration
-      }
-  }
-
-  /**
-   * Try to run the above code to see how the compiler informs us that
+   * {{{
+   * def unexhaustive(): Unit = {
+   * sealed trait Symbol
+   * case class Note(name: String, duration: String, octave: Int) extends Symbol
+   * case class Rest(duration: String)                            extends Symbol
+   *
+   * def nonExhaustiveDuration(symbol: Symbol): String =
+   *   symbol match {
+   *     case Rest(duration) => duration
+   *   }
+   * }
+   *}}}
+   *
+   * If we try to run the above code to see how the compiler informs us that
    * we don’t handle all the cases in `nonExhaustiveDuration`.
    *
    * = Equals =

src/test/scala/scalatutorial/sections/ClassesVsCaseClassesSpec.scala

@@ -19,4 +19,10 @@ class ClassesVsCaseClassesSpec extends Spec with Checkers {
   def `check equality`: Unit =
     check(Test.testSuccess(ClassesVsCaseClasses.equality _, false :: true :: HNil))
 
+  def `check encoding`: Unit =
+    check(
+      Test.testSuccess(
+        ClassesVsCaseClasses.encoding _,
+        "Note(C,Quarter,3)" :: false :: "Note(C,Quarter,4)" :: HNil))
+
 }