C#

if (statusHandler != null)     <--- that looks like a null-test
    // Invoke the delegate
    statusHandler(null, e);    <--- according to the comment this is an invocation

John Simmons / outlaw programmer wrote:

Does anyone have any ideas?

Employee2 empl = null;
if (obj is Employee2)
   empl = (Employee2)obj;

Employee2 empl = obj as Employee2;

"Employee2" -> Property1 x Property2

[ListViewProps("Propery1", "Not Applicable")]
class Employee1
{

}

[ListViewProps("Propery1", "Property2")]
class Employee2
{

}

DaveyM69 wrote:

either throw a NotImplementedException

DaveyM69 wrote:

or return String.Empty / "Not applicable" for the unused property.

John Simmons / outlaw programmer wrote:

Can you give me an example

// IEmployee.cs

namespace EmployeeTestApp
{
    public interface IEmployee
    {
        string Property1
        {
            get;
            set;
        }
        string Property2
        {
            get;
            set;
        }
    }
}

// Employee1.cs

namespace EmployeeTestApp
{
    public class Employee1 : IEmployee
    {
        private string m_Property1;
        private string m_Property2;

        // default constructor if needed
        public Employee1()
            : this("Unknown")
        { }
        public Employee1(string property1)
        {
            m_Property1 = property1;
            m_Property2 = "Not applicable";
        }

        #region IEmployee Members

        public string Property1
        {
            get { return m_Property1; }
            set
            {
                if (m_Property1 != value)
                {
                    m_Property1 = value;
                    // raise event here if needed
                }
            }
        }

        public string Property2
        {
            get { return m_Property2; }
            set
            {
                // Ignore as not implemented 
            }
        }

        #endregion
    }
}

// Employee2.cs

namespace EmployeeTestApp
{
    public class Employee2 : IEmployee
    {
        private string m_Property1;
        private string m_Property2;

        // default constructor if needed
        public Employee2()
            : this("Unknown", "Unknown")
        { }
        public Employee2(string property1, string property2)
        {
            m_Property1 = property1;
            m_Property2 = property2;
        }

        #region IEmployee Members

        public string Property1
        {
            get { return m_Property1; }
            set
            {
                if (m_Property1 != value)
                {
                    m_Property1 = value;
                    // raise event here if needed
                }
            }
        }

        public string Property2
        {
            get { return m_Property2; }
            set
            {
                if (m_Property2 != value)
                {
                    m_Property2 = value;
                    // raise event here if needed
                }
            }
        }

        #endregion
    }
}

// Form1.cs

using System.Collections.Generic;
using System.Windows.Forms;

namespace EmployeeTestApp
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            // listView1 is ListView with two columns already
            InitializeComponent();
            // employee list
            List<IEmployee> employees = new List<IEmployee>();
            // add new Employee1 instance to list
            employees.Add(new Employee1(
                "Employee1 Instance, Property1"));
            // add new Employee2 instance to list
            employees.Add(new Employee2(
                "Employee2 Instance, Property1", "Property2"));
            // iterate over list creating item and subitem and add to ListView
            foreach(IEmployee employee in employees)
            {
                ListViewItem item = new ListViewItem(employee.Property1);
                ListViewItem.ListViewSubItem subItem = new ListViewItem.ListViewSubItem();
                subItem.Text = employee.Property2;
                item.SubItems.Add(subItem);
                listView1.Items.Add(item);
            }
        }
    }
}

get { throw new NotImplementedException("Not Applicable"); }

try
{
    subItem.Text = employee.Property2;
}
catch (NotImplementedException ex)
{
    subItem.Text = ex.Message;
}

John Simmons / outlaw programmer wrote:

isn't appropriate because it destroys the object-oriented aspect of the code

public static implicit operator Employee2(Employee1 value)
{
    return new Employee2(value.Property1, "Not Applicable");
}