C#

using System;
using System.Collections;
using System.ComponentModel;
using System.Globalization;
using System.ComponentModel.Design.Serialization;
using System.Reflection;
 
namespace Holidays
{
    public class YourControl
    {
        private readonly HolidayCollection holidays = new HolidayCollection();
 
        // This attribute tells the code generator to serialize the contained items
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
        public HolidayCollection Holidays
        {
            get { return holidays; }
        }
    }
 
 
    // The strongly typed collection
    // Never expose an ArrayList or an Array as a public property!
    public class HolidayCollection : CollectionBase
    {
        public int Add(Holiday item)
        { return List.Add(item); }
 
        public Holiday this[int index]
        {
            get { return (Holiday)List[index]; }
            set { List[index] = value; }
        }
    }
 
 
    // assign the converter
    [TypeConverter(typeof(HolidayConverter))]
    public class Holiday
    {
        public Holiday()
        {
            this.month = -1;
            this.day = -1;
            this.reason = null;
        }
        
        public Holiday(int month, int day, string reason)
        {
            // add validation logic here
            this.month = month;
            this.day = day;
            this.reason = reason;
        }
 
        private int month;
        private int day;
        private string reason;
 
        public int Month
        {
            get { return month; }
            set { month = value; }
        }
 
        public int Day
        {
            get { return day; }
            set { day = value; }
        }
 
        public string Reason
        {
            get { return reason; }
            set { reason = value; }
        }
    }
 
 
    // The converter for Holiday. It's main purpose is to support code generation
    // It also makes the object "expandable", like e.g. Point or Size.
    internal class HolidayConverter : ExpandableObjectConverter
    {
        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
        {
            // An InstanceDescriptor is required for code generation
            if (destinationType == typeof(InstanceDescriptor))
                return true;
 
            // delegate other conversions
            return base.CanConvertTo(context, destinationType);
        }
 
 
        public override object ConvertTo(ITypeDescriptorContext context, 
            CultureInfo culture, object value, Type destinationType)
        {
            // cast value
            Holiday holiday = value as Holiday;
 
            // the InstanceDescriptor is used by the CodeGenerator to
            // get information about how to construct the value
            if (destinationType == typeof(InstanceDescriptor) && holiday != null)
            {
                // the arguments of the constructor (int month, int day, string reason)
                Type[] argumentTypes = new Type[] { typeof(int), typeof(int), typeof(string) };
 
                // get the constructor
                ConstructorInfo constructor = typeof(Holiday).GetConstructor(argumentTypes);
 
                // array with the actual constructor arguments
                object[] arguments = new object[] { holiday.Month, holiday.Day, holiday.Reason };
 
                if (constructor != null)
                    // return the instance descriptor
                    return new InstanceDescriptor(constructor, arguments, false);
            }
 
            // delegate other conversions
            return base.ConvertTo(context, culture, value, destinationType);
        }
    }
}