avoid-return-keyword.md

Topic	Avoid Return Keyword in Scala
Git sample	AvoidReturnTest.scala

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• STATEMENT VS EXPRESSION: A Statement Executes while An Expression Evaluates to a Value

• In Java, there is a practice of using keyword return at the end of a method. You can do the same in Scala, Example below shows it

    /* Scala code below resembles Java */
    def getErrorMessageWithReturnFirst(errorCode: Int): String = {
  
  	/* A variable ('var') type which can change after declaration */
  	var result: String = "Unknown Error"
  
  	errorCode match {
  	  case 1 => result = "TCP Socket Failure"
  	  case 2 => result = "UDP Failure"
  	  case 3 => result = "Unknown Error"
  	}
  
  	/* Return the result */
  	return result
    }

• Scala code above can be improved with the help of expression-oriented syntax, Below given Scala code shows how match returns result

    /* Scala code below still resembles Java */
    def getErrorMessageWithExplicitReturnSecond(errorCode: Int): String = {
  
  	/* A value ('val') type which can't change after declaration */
  	val result = errorCode match {
  	  case 1 => "TCP Socket Failure"
  	  case 2 => "UDP Failure"
  	  case 3 => "Unknown Error"
  	}
  
  	/* Return the result */
  	return result
    }

• Scala code can be improved further, by removing val result declaration

    /* Scala code below somewhat resembles Java */
    def getErrorMessageWithExplicitReturnThird(errorCode: Int): String = {
  
  	/* Control structure 'match' is returning a String */
  	return errorCode match { case 1 => "TCP Socket Failure" case 2 => "UDP Failure" case 3 => "Unknown Error" }
    }

• NO RETURN STATEMENT: An expression evaluates to a value, so there’s no need of return

   /* Scala code below rarely resembles Java */
    def getErrorMessageWithoutReturn(errorCode: Int): String = {
  
  	/* Control structure 'match' is the last statement in this method; automatically taken as return value */
  	errorCode match { case 1 => "TCP Socket Failure" case 2 => "UDP Failure" case 3 => "Unknown Error" }
    }

• Avoid return statement and prefer to have the last expression be the return value