How to prevent duplicate code in different for loops?

I've got a class, let's say a "mutual fund portfolio". It's got 3 methods that calculate 3 different numbers each using a for-loop. Most of the steps in the 3 different methods are exactly the same, except for 1 or 2 steps.
Is there a smarter way to prevent duplicate code than just writing 1 base method and using a case statement for the 3 different numbers to be calculated? I looked at the "Template Method Design Pattern" but that doesn't seem to be applicable.

You can find some simplified code underneath. The difference is in the "DoCalculationsWithMemberVariables_Step3" step of the "Test_MeasureX_Historically" methods. Those differ.

Public Class MutualFundsPortfolio


     Public Sub Test_Measure1_Historically()
       Dim j As Integer
       Dim lNrOfPeriods As Integer
       lNrOfPeriods = 20 
       For j = 1 To lNrOfPeriods 
         DoCalculationsWithMemberVariables_Step1
         DoCalculationsWithMemberVariables_Step2
         DoCalculationsWithMemberVariables_Step3a
         DoCalculationsWithMemberVariables_Step4 
       Next j
     End Sub 
   
     Public Sub Test_Measure2_Historically()
       Dim j As Integer
       Dim lNrOfPeriods As Integer
       lNrOfPeriods = 20 
       For j = 1 To lNrOfPeriods 
         DoCalculationsWithMemberVariables_Step1
         DoCalculationsWithMemberVariables_Step2
         DoCalculationsWithMemberVariables_Step3b
         DoCalculationsWithMemberVariables_Step4 
       Next j
     End Sub 
   

     Public Sub Test_Measure3_Historically()
       Dim j As Integer
       Dim lNrOfPeriods As Integer
       lNrOfPeriods = 20 
       For j = 1 To lNrOfPeriods 
         DoCalculationsWithMemberVariables_Step1
         DoCalculationsWithMemberVariables_Step2
         DoCalculationsWithMemberVariables_Step3c
         DoCalculationsWithMemberVariables_Step4 
       Next j
     End Sub 
   End Class

G. Van Dam, Jan 04, 2011

Reply 1

Hi, I thought I'd take a crack at this. I'm still learning like you, and this is what I came up with. It's a small VS 2008 Console project that uses the Strategy Pattern and other cool stuff. It's probably not exactly what you need but it does what you need without duplicating code.

This was kind of fun. Three years ago I could never do this.

Here's some code from the attached file example.

class Program
     {
         static void Main(string[] args)
         {

             Console.WriteLine("Enter one of the following values:");
             Console.WriteLine("   Test1, Test2, or Test3");

             // Read the input value
             // Valid values are: Test1, Test2, Test3
             string testType = Console.ReadLine();

             // Convert the string type to the Enum type.
             HistoricalItems key = (HistoricalItems)Enum.Parse(typeof(HistoricalItems), testType.ToLower());

             // Instantiate a new Portfolio context.
             MutualFundsPorfolio portfolio = new MutualFundsPorfolio();

             // Process the selected item type.
             portfolio.Process(key);

             Console.ReadLine();
         }
     }

You can download the file here: http://www.kingwilder.com/downloads/strategyexample.zip - 51KB - VS 2008 project
This zip file contains both VB.Net and C# examples.

I hope it helps.

King Wilder

King Wilder, Jan 04, 2011