'Usage

Dim instance As DynamicObject
Dim binder As GetIndexBinder
Dim indexes As Object()
Dim result As Object
Dim returnValue As Boolean

returnValue = instance.TryGetIndex(binder, _
    indexes, result)

'Declaration

Public Overridable Function TryGetIndex ( _
    binder As GetIndexBinder, _
    indexes As Object(), _
    <OutAttribute> ByRef result As Object _
) As Boolean

Imports System.Linq.Expressions
Imports System.Dynamic

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

    ' The inner dictionary to store field names and values.
    Dim dictionary As New Dictionary(Of String, Object)

    ' Get the property value.
    Public Overrides Function TryGetMember(
        ByVal binder As System.Dynamic.GetMemberBinder, 
        ByRef result As Object) As Boolean

        Return dictionary.TryGetValue(binder.Name, result)

    End Function

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

        dictionary(binder.Name) = value
        Return True

    End Function

    ' Set the property value by index.
    Public Overrides Function TrySetIndex(
        ByVal binder As System.Dynamic.SetIndexBinder,
        ByVal indexes() As Object, ByVal value As Object) As Boolean

        Dim index As Integer = CInt(indexes(0))
        ' If a corresponding property already exists, set the value.
        If (dictionary.ContainsKey("Property" & index)) Then
            dictionary("Property") = value
        Else
            ' If a property does not exist, create it.
            dictionary.Add("Property" & index, value)
        End If
        Return True
    End Function

    ' Get the property value by index.
    Public Overrides Function TryGetIndex(
        ByVal binder As System.Dynamic.GetIndexBinder,
        ByVal indexes() As Object, ByRef result As Object) As Boolean

        Dim index = CInt(indexes(0))
        Return dictionary.TryGetValue("Property" & index, result)
    End Function
End Class


Module Module1
    Sub Main()

        ' Creating a dynamic object.
        Dim sampleObject As Object = New SampleDynamicObject()

        ' Creating Property0.
        ' The TrySetMember method is called.
        sampleObject.Property0 = "Zero"

        ' Getting the value by index.
        ' The TryGetIndex method is called.
        Console.WriteLine(sampleObject(0))

        ' Setting the property value by index.
        ' The TrySetIndex method is called.
        ' (This method also creates Property1.)
        sampleObject(1) = 1

        ' Getting the Property1 value.
        ' The TryGetMember method is called.
        Console.WriteLine(sampleObject.Property1)

        ' The following statement produces a run-time exception
        ' because there is no corresponding property.
        ' Console.WriteLine(sampleObject(2))
    End Sub
End Module

' This code example produces the following output:

' Zero
' 1