ColumnView.CustomUnboundColumnData Event

using DevExpress.XtraGrid.Views.Base;
using DevExpress.XtraGrid.Views.Grid;
using DevExpress.XtraGrid.Columns;

private void Form1_Load(object sender, System.EventArgs e) {
   // ... 
   gridControl1.ForceInitialize();

   // Create an unbound column. 
   GridColumn unbColumn = gridView1.Columns.AddField("Total");
   unbColumn.VisibleIndex = gridView1.Columns.Count;
   unbColumn.UnboundType = DevExpress.Data.UnboundColumnType.Decimal;
   // Disable editing. 
   unbColumn.OptionsColumn.AllowEdit = false;
   // Specify format settings. 
   unbColumn.DisplayFormat.FormatType = DevExpress.Utils.FormatType.Numeric;
   unbColumn.DisplayFormat.FormatString = "c";
   // Customize the appearance settings. 
   unbColumn.AppearanceCell.BackColor = Color.LemonChiffon;
}

// Returns the total amount for a specific row. 
decimal getTotalValue(GridView view, int listSourceRowIndex) {
    decimal unitPrice = Convert.ToDecimal(view.GetListSourceRowCellValue(listSourceRowIndex, "UnitPrice"));
    decimal quantity = Convert.ToDecimal(view.GetListSourceRowCellValue(listSourceRowIndex, "Quantity"));
    decimal discount = Convert.ToDecimal(view.GetListSourceRowCellValue(listSourceRowIndex, "Discount"));
    return unitPrice * quantity * (1 - discount);
}

// Provides data for the Total column. 
private void gridView1_CustomUnboundColumnData(object sender, CustomColumnDataEventArgs e) {
   GridView view = sender as GridView;
   if (e.Column.FieldName == "Total" && e.IsGetData) e.Value = 
     getTotalValue(view, e.ListSourceRowIndex);
}

Imports DevExpress.XtraGrid.Views.Base
Imports DevExpress.XtraGrid.Views.Grid
Imports DevExpress.XtraGrid.Columns

Private Sub Form1_Load(ByVal sender As System.Object, _
  ByVal e As System.EventArgs) Handles MyBase.Load
   ' ... 
   gridControl1.ForceInitialize()

   ' Create an unbound column. 
   Dim unbColumn As GridColumn = GridView1.Columns.AddField("Total")
   unbColumn.VisibleIndex = GridView1.Columns.Count
   unbColumn.UnboundType = DevExpress.Data.UnboundColumnType.Decimal 
   ' Disable editing. 
   unbColumn.OptionsColumn.AllowEdit = False 
   ' Specify format settings. 
   unbColumn.DisplayFormat.FormatType = DevExpress.Utils.FormatType.Numeric
   unbColumn.DisplayFormat.FormatString = "c" 
   ' Customize the appearance settings. 
   unbColumn.AppearanceCell.BackColor = Color.LemonChiffon
End Sub 

' Returns the total amount for a specific row. 
Private Function getTotalValue(view As GridView, listSourceRowIndex As Integer) As Decimal 
    Dim unitPrice As Decimal = Convert.ToDecimal(view.GetListSourceRowCellValue(listSourceRowIndex, "UnitPrice"))
    Dim quantity As Decimal = Convert.ToDecimal(view.GetListSourceRowCellValue(listSourceRowIndex, "Quantity"))
    Dim discount As Decimal = Convert.ToDecimal(view.GetListSourceRowCellValue(listSourceRowIndex, "Discount"))
    Return unitPrice * quantity * (1 - discount)
End Function 

' Provides data for the Total column. 
Private Sub GridView1_CustomUnboundColumnData(ByVal sender As Object, _
  ByVal e As CustomColumnDataEventArgs) Handles GridView1.CustomUnboundColumnData
   Dim view As GridView = TryCast(sender, GridView)
   If e.Column.FieldName = "Total" AndAlso e.IsGetData Then 
      e.Value = getTotalValue(view, e.ListSourceRowIndex)
   End If 
End Sub 

using System;
using System.Collections.Generic;
using System.Data;

namespace WindowsApplication1
{
    public class MyCache
    {

        private readonly string _KeyFieldName;
        Dictionary<object, object> valuesCache = new Dictionary<object, object>();

        public MyCache(string keyFieldName)
        {
            _KeyFieldName = keyFieldName;            
        }

        public object GetKeyByRow(object row)
        {
            return (row as DataRowView)[_KeyFieldName];
        }


        public object GetValue(object row)
        {
            return GetValueByKey(GetKeyByRow(row));
        }                                               

        public object GetValueByKey(object key)
        {
            object result = null;
            valuesCache.TryGetValue(key, out result);
            return result;
        }


        public void SetValue(object row, object value)
        {
            SetValueByKey(GetKeyByRow(row), value);
        }

        public void SetValueByKey(object key, object value)
        {
            valuesCache[key] = value;
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using DevExpress.XtraGrid.Columns;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        private DataColumn _KeyField;
        private DataTable _Tbl;
        private MyCache _Cache = new MyCache("ID");
        private DataTable CreateTable(int RowCount)
        {
            _Tbl = new DataTable();
            _KeyField = _Tbl.Columns.Add("ID", typeof(int));
            _KeyField.ReadOnly = true;
            _KeyField.AutoIncrement = true;
            _Tbl.Columns.Add("Name", typeof(string));
            _Tbl.Columns.Add("Number", typeof(int));
            _Tbl.Columns.Add("Date", typeof(DateTime));
            for (int i = 0; i < RowCount; i++)
                _Tbl.Rows.Add(new object[] { null, String.Format("Name{0}", i), 3 - i, DateTime.Now.AddDays(i) });
            return _Tbl;
        }

        public Form1()
        {
            InitializeComponent();
            gridControl1.DataSource = CreateTable(20);
            CreateUnboundColumn();
        }
        private void CreateUnboundColumn()
        {
            GridColumn col = gridView1.Columns.AddVisible("Unbound", "Unbound column");
            col.UnboundType = DevExpress.Data.UnboundColumnType.String;
        }



        private void gridView1_CustomUnboundColumnData(object sender, DevExpress.XtraGrid.Views.Base.CustomColumnDataEventArgs e)
        {
            if (e.IsGetData)
                e.Value = _Cache.GetValue(e.Row);
            if (e.IsSetData)
                _Cache.SetValue(e.Row, e.Value);
        }
    }
}

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Text
Imports System.Windows.Forms
Imports DevExpress.XtraGrid.Columns

Namespace WindowsApplication1
    Partial Public Class Form1
        Inherits Form
        Private _KeyField As DataColumn
        Private _Tbl As DataTable
        Private _Cache As New MyCache("ID")
        Private Function CreateTable(ByVal RowCount As Integer) As DataTable
            _Tbl = New DataTable()
            _KeyField = _Tbl.Columns.Add("ID", GetType(Integer))
            _KeyField.ReadOnly = True
            _KeyField.AutoIncrement = True
            _Tbl.Columns.Add("Name", GetType(String))
            _Tbl.Columns.Add("Number", GetType(Integer))
            _Tbl.Columns.Add("Date", GetType(DateTime))
            For i As Integer = 0 To RowCount - 1
                _Tbl.Rows.Add(New Object() { Nothing, String.Format("Name{0}", i), 3 - i, DateTime.Now.AddDays(i) })
            Next i
            Return _Tbl
        End Function

        Public Sub New()
            InitializeComponent()
            gridControl1.DataSource = CreateTable(20)
            CreateUnboundColumn()
        End Sub
        Private Sub CreateUnboundColumn()
            Dim col As GridColumn = gridView1.Columns.AddVisible("Unbound", "Unbound column")
            col.UnboundType = DevExpress.Data.UnboundColumnType.String
        End Sub



        Private Sub gridView1_CustomUnboundColumnData(ByVal sender As Object, ByVal e As DevExpress.XtraGrid.Views.Base.CustomColumnDataEventArgs) Handles gridView1.CustomUnboundColumnData
            If e.IsGetData Then
                e.Value = _Cache.GetValue(e.Row)
            End If
            If e.IsSetData Then
                _Cache.SetValue(e.Row, e.Value)
            End If
        End Sub
    End Class
End Namespace

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Data

Namespace WindowsApplication1
    Public Class MyCache

        Private ReadOnly _KeyFieldName As String
        Private valuesCache As New Dictionary(Of Object, Object)()

        Public Sub New(ByVal keyFieldName As String)
            _KeyFieldName = keyFieldName
        End Sub

        Public Function GetKeyByRow(ByVal row As Object) As Object
            Return (TryCast(row, DataRowView))(_KeyFieldName)
        End Function


        Public Function GetValue(ByVal row As Object) As Object
            Return GetValueByKey(GetKeyByRow(row))
        End Function

        Public Function GetValueByKey(ByVal key As Object) As Object
            Dim result As Object = Nothing
            valuesCache.TryGetValue(key, result)
            Return result
        End Function


        Public Sub SetValue(ByVal row As Object, ByVal value As Object)
            SetValueByKey(GetKeyByRow(row), value)
        End Sub

        Public Sub SetValueByKey(ByVal key As Object, ByVal value As Object)
            valuesCache(key) = value
        End Sub
    End Class
End Namespace