C#

public object Key
{
    get
    {
        return this.List[List.Count-1]; //Allways returns the last member of the List
    }
    set
    {
        if(!this.List.Contains(value))
        {
            this.List.Add(value);
        }
    }
}

Tim Paaschen wrote:

This is a really strange idea!

Tim Paaschen wrote:

and provide a property for each possible key

Martin# wrote:

Think about that again! ...

Tim Paaschen wrote:

I never said that it is a good idea

Tim Paaschen wrote:

just that it is technically possible

using System.Collections.Generic;
using System;

namespace Generics.Test
{
  public class TestGeneric
  {
    public TestGeneric()
    {
      MyList<MyTest> test = new MyList<MyTest>();
      test.Add(new MyTest("Test 1"));
      test.Add(new MyTest("Test 2"));
      if (test.HasValue("Test 2"))
        Console.WriteLine("Test 2 is present");
    }
  }

  public interface ISomeValue
  {
    string SomeValue { get; set; }
  }
  public class MyList<T> : List<T>, IEnumerable<T> where T : ISomeValue
  {
    public bool HasValue(string key)
    {
      foreach (T item in this)
      {
        if (item != null && item.SomeValue == key)
            return true;
      }
      return false;
    }

    #region IEnumerable<T> Members

    IEnumerator<T> IEnumerable<T>.GetEnumerator()
    {
       for (int i = 0; i < this.Count; i++)
       {
          yield return this[i];
       }
    }

    #endregion

    #region IEnumerable Members

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
      throw new Exception("The method or operation is not implemented.");
    }

    #endregion
  }
}

<br />
    public interface RequestCollectionInterface<br />
    {<br />
        ImageList Images { get; set; }<br />
        int OpenCount { get; }<br />
        int PendingCount { get; }<br />
        int ImmediateCount { get; }<br />
        int HighCount { get; }<br />
    }<br />
    public class RequestCollection<T> : List<T>, IEnumerable<T> where T : RequestCollectionInterface<br />
    {<br />
        IEnumerator<T> IEnumerable<T>.GetEnumerator()<br />
        {<br />
            for (int i = 0; i < this.Count; i++)<br />
            {<br />
                yield return this[i];<br />
            }<br />
        }<br />
        IEnumerator IEnumerable.GetEnumerator()<br />
        {<br />
            throw new Exception("The method or operation is not implemented.");<br />
        }<br />
        public int OpenCount<br />
        {<br />
            get<br />
            {<br />
                int ReturnValue = 0;<br />
                foreach (Request item in this)<br />
                {<br />
                    if (item.Status == RequestStatus.Open)<br />
                        ReturnValue++;<br />
                }<br />
                return ReturnValue;<br />
            }<br />
        }<br />
        public int PendingCount<br />
        {<br />
            get<br />
            {<br />
                int ReturnValue = 0;<br />
                foreach (Request item in this)<br />
                {<br />
                    if (item.Status == RequestStatus.Pending)<br />
                        ReturnValue++;<br />
                }<br />
                return ReturnValue;<br />
            }<br />
        }<br />
        public int ImmediateCount<br />
        {<br />
            get<br />
            {<br />
                int ReturnValue = 0;<br />
                foreach (Request item in this)<br />
                {<br />
                    if (item.Priority = RequestPriority.Immediate)<br />
                        ReturnValue++;<br />
                }<br />
                return ReturnValue;<br />
            }<br />
        }<br />
        public int HighCount<br />
        {<br />
            get<br />
            {<br />
                int ReturnValue = 0;<br />
                foreach (Request item in this)<br />
                {<br />
                    if (item.Priority = RequestPriority.High)<br />
                        ReturnValue++;<br />
                }<br />
                return ReturnValue;<br />
            }<br />
        }<br />
    }<br />

<br />
<br />
        private RequestCollection<Request> __GetRequests()<br />
        {<br />
            RequestCollection<Request> rc = new RequestCollection<Request>();<br />
            Request r = new Request();<br />
            r.Id = 1;<br />
            r.Summary = "This is a test";<br />
            r.To = "Test";<br />
            r.From = new User();<br />
            r.Priority = RequestPriority.Normal;<br />
            r.Status = RequestStatus.Open;<br />
            r.Created = DateTime.Now;<br />
            r.Assigned = r.Created;<br />
            r.Parent = rc;<br />
            r.Hours = r.Created.Subtract(r.Assigned).Hours;<br />
<br />
            rc.Add(r);<br />
            return rc;<br />
        }<br />

<br />
Error	3	The type 'HelpDesk.Request' must be convertible to 'HelpDesk.RequestCollectionInterface' in order to use it as parameter 'T' in the generic type or method 'HelpDesk.RequestCollection<T>'	C:\Documents and Settings\Administrator\My Documents\Visual Studio 2005\Projects\HelpDesk\HelpDesk\DataAccess.cs	66	44	HelpDesk<br />

<br />
    class Request<br />
    {<br />
        private int _Id;<br />
        private string _Summary;<br />
        private User _From;<br />
        private string _To;<br />
        private RequestPriority _Priority;<br />
        private RequestStatus _Status;<br />
        private DateTime _Created;<br />
        private DateTime _Assigned;<br />
        private DateTime _LastChanged;<br />
        private double _Hours;<br />
        private RequestCollection<Request> _Parent;<br />
<br />
        public int Id<br />
        {<br />
            get { return _Id; }<br />
            set { _Id = value; }<br />
        }<br />
        public string Summary<br />
        {<br />
            get { return _Summary; }<br />
            set { _Summary = value; }<br />
        }<br />
        public User From<br />
        {<br />
            get { return _From; }<br />
            set { _From = value; }<br />
        }<br />
        public string To<br />
        {<br />
            get { return _To; }<br />
            set { _To = value; }<br />
        }<br />
        public RequestPriority Priority<br />
        {<br />
            get { return _Priority; }<br />
            set { _Priority = value; }<br />
        }<br />
        public RequestStatus Status<br />
        {<br />
            get { return _Status; }<br />
            set { _Status = value; }<br />
        }<br />
        public DateTime Created<br />
        {<br />
            get { return _Created; }<br />
            set { _Created = value; }<br />
        }<br />
        public DateTime Assigned<br />
        {<br />
            get { return _Assigned; }<br />
            set { _Assigned = value; }<br />
        }<br />
        public DateTime LastChanged<br />
        {<br />
            get { return _LastChanged; }<br />
            set { _LastChanged = value; }<br />
        }<br />
        public double Hours<br />
        {<br />
            get { return _Hours; }<br />
            set { _Hours = value; }<br />
        }<br />
        public RequestCollection<Request> Parent<br />
        {<br />
            get { return _Parent; }<br />
            set { _Parent = value; }<br />
        }<br />
        public Image PriorityImage<br />
        {<br />
            get<br />
            {<br />
                Image ReturnValue = null;<br />
                try<br />
                {<br />
                    if (this.Parent != null && this.Parent.Images != null)<br />
                        ReturnValue = this.Parent.Images.Images[(int)this.Priority];<br />
                }<br />
                catch (Exception ex)<br />
                {<br />
                    int i = 99;<br />
                }<br />
                return ReturnValue;<br />
            }<br />
        }<br />
    }<br />

using System;
using System.Collections.Generic;
using System.Text;

namespace TestIterator
{
  class Program
  {
    static void Main(string[] args)
    {
      RequestItemCollection<Request> coll = new RequestItemCollection<Request>();
      Request req = new Request();
      req.Status = RequestStatus.Open;
      coll.Add(req);
      req = new Request();
      req.Status = RequestStatus.Open;
      coll.Add(req);
      System.Console.WriteLine("Open count = {0}", coll.OpenCount);
      Console.ReadLine();
    }
  }

  public class RequestItemCollection<T> : List<T>, IEnumerable<T> where T: IStatus
  {
    #region IEnumerable<T> Members

    IEnumerator<T> IEnumerable<T>.GetEnumerator()
    {
      for (int i = 0; i < this.Count; i++)
        yield return this[i];
    }

    #endregion

    #region IEnumerable Members

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
      throw new Exception("The method or operation is not implemented.");
    }

    #endregion

    public int OpenCount
    {
      get
      {
        return StatusCount(RequestStatus.Open);
      }
    }

    public int Closed
    {
      get
      {
        return StatusCount(RequestStatus.Closed);
      }
    }

    private int StatusCount(RequestStatus status)
    {
      int count = 0;

      foreach (T item in this)
      {
        if (item.Status == status)
          count++;
      }
      return count;
    }
  }

  public enum RequestStatus
  {
    Open,
    Closed,
    Pending
  }
  public interface IStatus
  {
    RequestStatus Status { get; set; }
  }

  public class Request : IStatus
  {
    private RequestStatus _status;
    #region IStatus Members

    public RequestStatus Status
    {
      get
      {
        return _status;
      }
      set
      {
        _status = value;
      }
    }

    #endregion
  }
}