clarified the constructor matching code

Author: tobyweston

…r18/BasicConstructorPatternExample.scala …18/BasicConstructorPatternExample1.scalasrc/main/scala/s4j/scala/chapter18/BasicConstructorPatternExample.scala renamed to src/main/scala/s4j/scala/chapter18/BasicConstructorPatternExample1.scala src/main/scala/s4j/scala/chapter18/BasicConstructorPatternExample.scala renamed to src/main/scala/s4j/scala/chapter18/BasicConstructorPatternExample1.scala

@@ -16,14 +16,13 @@
 
 package s4j.scala.chapter18
 
-object BasicConstructorPatternExample extends App {
+object BasicConstructorPatternExample1 extends App {
 
   val hero = new SuperHero("Batman", "Bruce Wayne", List("Speed", "Agility", "Strength"))
 
   hero match {
     case SuperHero(_, "Bruce Wayne", _) => println("I'm Batman!")
-    case SuperHero(_, _, _)             => println("I'm Batman!")
-    case _                              => println("I'm a civilian")
+    case SuperHero(_, _, _)             => println("???")
   }
 
 }

src/main/scala/s4j/scala/chapter18/BasicConstructorPatternExample2.scala

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2015-2017 Toby Weston
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package s4j.scala.chapter18
+
+object BasicConstructorPatternExample2 extends App {
+
+  val hero = new Person("Joe Ordinary")
+
+  // produces a 'MatchError' as a Person doesn't match anything
+  hero match {
+    case SuperHero(_, "Bruce Wayne", _) => println("I'm Batman!")
+    case SuperHero(_, _, _)             => println("???")
+  }
+
+}

src/main/scala/s4j/scala/chapter18/BasicConstructorPatternExample3.scala

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2015-2017 Toby Weston
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package s4j.scala.chapter18
+
+object BasicConstructorPatternExample3 extends App {
+
+  val hero = new Person("Joe Ordinary")
+
+  // adding the wildcard _ means Joe matches the last case
+  hero match {
+    case SuperHero(_, "Bruce Wayne", _) => println("I'm Batman!")
+    case SuperHero(_, _, _)             => println("???")
+    case _                              => println("I'm a civilian")
+  }
+
+}