C#

Hashtable serializers = new Hashtable();

// Use the constructor that takes a type and XmlRootAttribute.
XmlSerializer s = new XmlSerializer(typeof(MyClass), myRoot);

// Implement a method named GenerateKey that creates unique keys 
// for each instance of the XmlSerializer. The code should take 
// into account all parameters passed to the XmlSerializer 
// constructor.
object key = GenerateKey(typeof(MyClass), myRoot);

// Check the local cache for a matching serializer.
XmlSerializer ser = (XmlSerializer)serializers[key];
if (ser == null) 
{
    ser = new XmlSerializer(typeof(MyClass), myRoot);
    // Cache the serializer.
    serializers[key] = ser;
}
else
{
    // Use the serializer to serialize, or deserialize.
}