Introduction to Composite WPF (CAL, Prism): Part 2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Data.Linq;
using System.Text;
using System.Xml.Serialization;
using System.Collections.Specialized;
using System.Xml;
using System.Windows.Documents;

namespace JamSoft.CALDemo.Modules.SettingsManager
{
    [Serializable]
    public class PropertiesCollection : IXmlSerializable
    {
        private NameValueCollection _properties = new NameValueCollection();
        private List<string> _keys = new List<string>();

        internal PropertiesCollection()
        {
        }

        public void SetSetting(string key, object value)
        {
            if (!_keys.Contains(key))
            {
                _properties.Add(key, value.ToString());
                _keys.Add(key);
            }
            else
            {
                _properties.Set(key, value.ToString());
            }
        }

        public object GetSettingValue(string key)
        {
            return _properties[key];
        }

        public System.Xml.Schema.XmlSchema GetSchema()
        {
            return null;
        }

        public void ReadXml(XmlReader reader)
        {
            _properties = new NameValueCollection();

            reader.Read();
            while (reader.MoveToNextAttribute())
            {
                _properties.Add(reader.Name, reader.Value);
            }

            _keys = _properties.AllKeys.ToList();
        }

        public void WriteXml(XmlWriter writer)
        {
            foreach (string key in _properties.Keys)
            {
                writer.WriteStartElement("property");
                string value = _properties[key];
                writer.WriteAttributeString(key, value);
                writer.WriteEndElement();
            }
        }
    }
}