DynamicObject Class

' The class derived from DynamicObject.
Public Class DynamicDictionary
    Inherits DynamicObject

    ' The inner dictionary.
    Dim dictionary As New Dictionary(Of String, Object)

    ' This property returns the number of elements
    ' in the inner dictionary.
    ReadOnly Property Count As Integer
        Get
            Return dictionary.Count
        End Get
    End Property


    ' If you try to get a value of a property that is
    ' not defined in the class, this method is called.

    Public Overrides Function TryGetMember(
        ByVal binder As System.Dynamic.GetMemberBinder,
        ByRef result As Object) As Boolean

        ' Converting the property name to lowercase
        ' so that property names become case-insensitive.
        Dim name As String = binder.Name.ToLower()

        ' If the property name is found in a dictionary,
        ' set the result parameter to the property value and return true.
        ' Otherwise, return false.
        Return dictionary.TryGetValue(name, result)
    End Function

    Public Overrides Function TrySetMember(
        ByVal binder As System.Dynamic.SetMemberBinder,
        ByVal value As Object) As Boolean

        ' Converting the property name to lowercase
        ' so that property names become case-insensitive.
        dictionary(binder.Name.ToLower()) = value

        ' You can always add a value to a dictionary,
        ' so this method always returns true.
        Return True
    End Function
End Class

Sub Demo(outputBlock As System.Windows.Controls.TextBlock)
    ' Creating a dynamic dictionary.
    Dim person As Object = New DynamicDictionary()

    ' Adding new dynamic properties.
    ' The TrySetMember method is called.
    person.FirstName = "Ellen"
    person.LastName = "Adams"

    ' Getting values of the dynamic properties.
    ' The TryGetMember method is called.
    ' Note that property names are now case-insensitive,
    ' although they are case-sensitive in C#.
    outputBlock.Text &= person.firstname & " " & person.lastname & vbCrLf

    ' Getting the value of the Count property.
    ' The TryGetMember is not called, 
    ' because the property is defined in the class.
    outputBlock.Text &= "Number of dynamic properties:" & person.Count & vbCrLf

    ' The following statement throws an exception at run time.
    ' There is no "address" property,
    ' so the TryGetMember method returns false and this causes
    ' a MissingMemberException.
    ' outputBlock.Text &= person.address & vbCrLf
End Sub
' This examples has the following output:
' Ellen Adams
' Number of dynamic properties: 2

// The class derived from DynamicObject.
public class DynamicDictionary : DynamicObject
{
   // The inner dictionary.
   Dictionary<string, object> dictionary
       = new Dictionary<string, object>();

   // This property returns the number of elements
   // in the inner dictionary.
   public int Count
   {
      get
      {
         return dictionary.Count;
      }
   }

   // If you try to get a value of a property 
   // not defined in the class, this method is called.
   public override bool TryGetMember(
       GetMemberBinder binder, out object result)
   {
      // Converting the property name to lowercase
      // so that property names become case-insensitive.
      string name = binder.Name.ToLower();

      // If the property name is found in a dictionary,
      // set the result parameter to the property value and return true.
      // Otherwise, return false.
      return dictionary.TryGetValue(name, out result);
   }

   // If you try to set a value of a property that is
   // not defined in the class, this method is called.
   public override bool TrySetMember(
       SetMemberBinder binder, object value)
   {
      // Converting the property name to lowercase
      // so that property names become case-insensitive.
      dictionary[binder.Name.ToLower()] = value;

      // You can always add a value to a dictionary,
      // so this method always returns true.
      return true;
   }
}

class Example
{
   private static System.Windows.Controls.TextBlock outputBlock;

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {

      Example.outputBlock = outputBlock;
      // Creating a dynamic dictionary.
      dynamic person = new DynamicDictionary();

      // Adding new dynamic properties. 
      // The TrySetMember method is called.
      person.FirstName = "Ellen";
      person.LastName = "Adams";

      // Getting values of the dynamic properties.
      // The TryGetMember method is called.
      // Note that property names are case-insensitive.
      outputBlock.Text += person.firstname + " " + person.lastname + "\n";

      // Getting the value of the Count property.
      // The TryGetMember is not called, 
      // because the property is defined in the class.
      outputBlock.Text +=
          "Number of dynamic properties:" + person.Count + "\n";

      // The following statement throws an exception at run time.
      // There is no "address" property,
      // so the TryGetMember method returns false and this causes a
      // RuntimeBinderException.
      // outputBlock.Text += person.address + "\n";
   }
}

// This example has the following output:
// Ellen Adams
// Number of dynamic properties: 2