Converting Methods to Functions

Author: CodeLab20

Functions/MethodsToFunctions.scala

@@ -0,0 +1,51 @@
+/**
+ * Methods can be converted into functions using partially applied functions
+ * Use an '_' to turn method parameters into function parameters
+ * If '_' is last character in method parameter, you can remove '_' 
+ * 
+ * */
+
+class Summer(x:Int)
+{
+  def addSingleInt(y:Int) = x + y
+  
+  def addTwoInts(y:Int, z:Int) = x + y + z 
+}
+
+class FunctionExecutor(z:Int)
+{
+    def runSingleParamFn(f:Int => Int) = f(z)
+    
+    def runTwoParamFn(f:(Int, Int) => Int) = f(z, 10)
+}
+
+object MethodsToFunctions extends App 
+{
+    val x = new Summer(10)
+    val singleFn = x.addSingleInt _
+    
+    println("singleFn.apply(20) : " + singleFn.apply(20))
+    println("singleFn(20) : " + singleFn(20))
+    
+    val z = new FunctionExecutor(20)
+    println("z.runSingleParamFn(singleFn) : " + z.runSingleParamFn(singleFn))
+    println("z.runSingleParamFn(x.addSingleInt _) :" + z.runSingleParamFn(x.addSingleInt _))   
+    println("z.runSingleParamFn(x.addSingleInt) :" + z.runSingleParamFn(x.addSingleInt))   
+    
+    val f2 = x.addTwoInts(40, _:Int)  //_ means parameter will be provided later
+    println("z.runSingleParamFn(f2) : " + z.runSingleParamFn(f2))
+    println("z.runTwoParamFn(x.addTwoInts) : " + z.runTwoParamFn(x.addTwoInts))
+    
+}
+
+/**
+ * Sample Output 
+singleFn.apply(20) : 30
+singleFn(20) : 30
+z.runSingleParamFn(singleFn) : 30
+z.runSingleParamFn(x.addSingleInt _) :30
+z.runSingleParamFn(x.addSingleInt) :30
+z.runSingleParamFn(f2) : 70
+z.runTwoParamFn(x.addTwoInts) : 40
+
+ */