Custom Class Constructor of an Inherited List<T>

S Lemen

HI,
    I have a class that inherits a List, where T the a custom class far below. The problem is creating the underlying list in the inheriting class constructor. The inheriting class is immediately below. How do I create the PerfAll List in the PerfAll constructor?
Thank you,
Scott
public class PerfAll : List<PerfCategory>
{
      private PerfAll _PerfAllCatCounters;

      public PerfAll()
      {
         _PerfAllCatCounters = new List<PerfCategory>(); // <-- this line is a compiler error
         PerfAll _All;
         PerfCategory _PerfCat;
         PerformanceCounterCategory[] _CounterCategories =  PerformanceCounterCategory.GetCategories();
         foreach (PerformanceCounterCategory cat in _CounterCategories)
         {
            _PerfCat = new PerfCategory(cat.CategoryName);
            _All.Add(_PerfCat);
         }
      _PerfAllCatCounters = _All;
   }
   public PerfAll PerformanceAllCatCounters
   {
      get
      {
            return _PerfAllCatCounters;
      }
   }
}

Custom class:
public class PerfCategory
{
   private string _CategoryName;
   private List<PerformanceCounter> _CounterList;
   public PerfCategory()
   {
      _CategoryName = string.Empty;
      _CounterList = new List<PerformanceCounter>();
   }
   public PerfCategory(string CategoryName)
      : this()
   {
      PerformanceCounter[] _CounterArray;
      _CategoryName = CategoryName;
      PerformanceCounterCategory _Counter = new PerformanceCounterCategory(CategoryName);
      _CounterArray = _Counter.GetCounters();

      foreach (PerformanceCounter counters in _CounterArray)
      {
         _CounterList.Add(counters);
      }

   }
   public string CategoryName
   {
      get
      {
         return _CategoryName;
      }
      set
      {
         _CategoryName = value;
      }
   }
   public List<PerformanceCounter> CounterList
   {
      get
      {
         return _CounterList;
      }
   }
}

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Afzal Pawaskar15y ago
Hi Scott,

You don't need to create the PerfAll List in the PerfAll constructor because the PerfAll class is actually a List itself as it inherits from List

Check this out:

public class PerfAll : List
    {
        //private PerfAll _PerfAllCatCounters;      //No need of this as PerfAll class is actually a list itself

        public PerfAll()
        {
            //_PerfAllCatCounters = new List(); // <-- this line is a compiler error because you are trying to inherit the other way around
            // If a class Car inherits from a class Vehicle, you can initialise Car car=new Vehicle() as every car is definitely a vehicle
            // but you cannot initialise Vehicle vehicle = new Car() as all vehicles are not neccessarily cars...
            //PerfAll _All;                         //No need of this as PerAll class is actually a list itself

            PerfCategory _PerfCat;
            PerformanceCounterCategory[] _CounterCategories = PerformanceCounterCategory.GetCategories();
            foreach (PerformanceCounterCategory cat in _CounterCategories)
            {
                _PerfCat = new PerfCategory(cat.CategoryName);
                //_All.Add(_PerfCat);                           //Not needed. Same reason as above

                base.Add(_PerfCat);                             //Surprised???Remember, PerfAll is a actually a list of type 'PerfCategory'...
            }
            //_PerfAllCatCounters = _All;                       //Not needed. Same reason as before
        }

        //public PerfAll PerformanceAllCatCounters              ///////////////////////////////////
        //{                                                     //Not needed. You can use:
        //    get                                               //PerfAll perfAll = new PerfAll();
        //    {                                                 //List list=perfAll;
        //        return _PerfAllCatCounters;                   //in your main() method. The car,
        //    }                                                 //vehicle example applies here...
        //}                                                     ///////////////////////////////////
    }

However, your problem doesn't end here. You are going to face issues relating to SingleInstance and MultiInstance Category Types which I hope you can take care of...^_^
Sam Hobbs15y ago
The PerformanceCounterCategory.GetCategories Method is static. It sure appears to me that you need to make your PerfAll class static. I am not sure if a class derived from List can be static but if not then perhaps the List should be embedded in the PerfAll class instead of derived from.