Rule Definition
This rule warns about a property accessed inside an iteration statement when the property returns a cloned object. In this case, multiple identical objects are created. If this is not the intent, access the property outside the iteration statement. Otherwise, multiple unnecessary objects are created and afterward, these objects must be garbage collected. This degrades performance, especially in compact iteration statements. Note that it is possible that such a construct is intended, and in that case this violation is perfectly acceptable like in the following case: public void BuildArrayOfArrayLists() { for(int i = 0; i < arrayOfLists.Length; i++) { arrayOfLists[i] = cloner.List; } }

Remediation
Whenever possible assign the property to a local variable outside the iteration statement and use the local variable inside the iteration statement.

Violation Code Sample

using System;
using System.Collections;

namespace BankingLibrary
{
   public class BankAccounts
   {
      ArrayList someList = new ArrayList();

      public ArrayList List
      {
         get{ return (ArrayList)someList.Clone(); }
      }

      public void ModifyList(object anything)
      {
         someList.Add(anything);
      }
   }

   public class Customer
   {
      BankAccounts accounts;
      ArrayList[] arrayOfLists;

      public Customer()
      {
         accounts = new BankAccounts();
         accounts.ModifyList("Money");
         arrayOfLists = new ArrayList[10];
      }

      // VIOLATION
      public void CustomerReport()
      {
         for(int i = 0; i < 10; i++) { Console.WriteLine(accounts.List); }
      }

   }
}

Fixed Code Sample

using System;
using System.Collections;

namespace BankingLibrary
{
   public class BankAccounts
   {
      ArrayList someList = new ArrayList();

      public ArrayList List
      {
         get{ return (ArrayList)someList.Clone(); }
      }

      public void ModifyList(object anything)
      {
         someList.Add(anything);
      }
   }

   public class Customer
   {
      BankAccounts accounts;
      ArrayList[] arrayOfLists;

      public Customer()
      {
         accounts = new BankAccounts();
         accounts.ModifyList("Money");
         arrayOfLists = new ArrayList[10];
      }

      // REMEDIATION
      public void CustomerReport()
      {
         ArrayList localAcccounts = accounts.List;

         for(int i = 0; i < 10; i++) { Console.WriteLine(localAcccounts); }
      }
   }
}

Microsoft Visual Studio 2005 - http://msdn.microsoft.com/en-us/library/ms182270(VS.80).aspx