Convert.ChangeType Wrapper that Handles Nullable Types

public static object ChangeType(object value, Type conversionType)
{
// Note: This if block was taken from Convert.ChangeType as is, and is needed here since we're
// checking properties on conversionType below.
  if (conversionType == null)
  {
    throw new ArgumentNullException("conversionType");
  } // end if
 
// If it's not a nullable type, just pass through the parameters to Convert.ChangeType
 
  if (conversionType.IsGenericType && 
    conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
  {
// It's a nullable type, so instead of calling Convert.ChangeType directly which would throw a
// InvalidCastException (per http://weblogs.asp.net/pjohnson/archive/2006/02/07/437631.aspx),
// determine what the underlying type is
// If it's null, it won't convert to the underlying type, but that's fine since nulls don't really
// have a type--so just return null
// Note: We only do this check if we're converting to a nullable type, since doing it outside
// would diverge from Convert.ChangeType's behavior, which throws an InvalidCastException if
// value is null and conversionType is a value type.
    if (value == null)
    {
      return null;
    } // end if
 
// It's a nullable type, and not null, so that means it can be converted to its underlying type,
// so overwrite the passed-in conversion type with this underlying type
    NullableConverter nullableConverter = new NullableConverter(conversionType);
    conversionType = nullableConverter.UnderlyingType;
  } // end if
 
// Now that we've guaranteed conversionType is something Convert.ChangeType can handle (i.e. not a
// nullable type), pass the call on to Convert.ChangeType
  return Convert.ChangeType(value, conversionType);
}