Public Overridable Function TrySetIndex ( _
    binder As SetIndexBinder, _
    indexes As Object(), _
    value As Object _
) As Boolean

Dim instance As DynamicObject
Dim binder As SetIndexBinder
Dim indexes As Object()
Dim value As Object
Dim returnValue As Boolean

returnValue = instance.TrySetIndex(binder, _
    indexes, value)

public virtual bool TrySetIndex(
    SetIndexBinder binder,
    Object[] indexes,
    Object value
)

public:
virtual bool TrySetIndex(
    SetIndexBinder^ binder, 
    array<Object^>^ indexes, 
    Object^ value
)

abstract TrySetIndex : 
        binder:SetIndexBinder * 
        indexes:Object[] * 
        value:Object -> bool 
override TrySetIndex : 
        binder:SetIndexBinder * 
        indexes:Object[] * 
        value:Object -> bool 

using System;
using System.Collections.Generic;
using System.Dynamic;
using System.Linq.Expressions;

// The class derived from DynamicObject.
public class SampleDynamicObject : DynamicObject
{
    // The inner dictionary to store field names and values.
    Dictionary<string, object> dictionary
        = new Dictionary<string, object>();

    // Get the property value.
    public override bool TryGetMember(
        GetMemberBinder binder, out object result)
    {
        return dictionary.TryGetValue(binder.Name, out result);
    }

    // Set the property value.
    public override bool TrySetMember(
        SetMemberBinder binder, object value)
    {
        dictionary[binder.Name] = value;
        return true;
    }

    // Set the property value by index.
    public override bool TrySetIndex(
        SetIndexBinder binder, object[] indexes, object value)
    {
        int index = (int)indexes[0];

        // If a corresponding property already exists, set the value.
        if (dictionary.ContainsKey("Property" + index))
            dictionary["Property"] = value;
        else
            // If a corresponding property does not exist, create it.
            dictionary.Add("Property" + index, value);
        return true;
    }         

    // Get the property value by index.
    public override bool TryGetIndex(
        GetIndexBinder binder, object[] indexes, out object result)
    {

        int index = (int)indexes[0];
        return dictionary.TryGetValue("Property" + index, out result);         
    }     
}
   
class Program
{
    static void Main(string[] args)
    {
        // Creating a dynamic object.
        dynamic sampleObject = 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]);
        Console.ReadLine();
    }
}

// This code example produces the following output:

// Zero
// 1

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