Custom Exception Framework: Using Enterprise Library Exception Handling Block

//--------------------------------------------
//  Author        : Santosh Poojari
//  Created Date  : 22/02/2008
//  Email ID      : santosh.poojari@gmail.com
//--------------------------------------------

#region References
using System;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections.Generic;

using Project.Practice.MVP.Domain;
using Project.Practice.MVP.Presenter;
using Project.Practice.MVP.Framework;
using Project.Practice.MVP.ExceptionHandling;
using Project.Practice.MVP.ExceptionHandling.CustomException;
#endregion

public partial class Calculation : CustomPage,ICalculationView
{
    #region Private Members
    private CalculationPresenter m_Presenter = null;
    #endregion
    protected void Page_Load(object sender, EventArgs e)
    {
        try
        {
            m_Presenter = new CalculationPresenter((ICalculationView)this);
            if (ViewState["USER_KEY_VALUE"] == null)
            {
                throw new ViewLayerException("Code Behind Exception");
            }
        }
        catch (Exception ex)
        {
            if (ExceptionHandleProvider.HandleException(ex, "Global Policy") == true)
            {
                throw ex;
            }
        }       
    }

    #region ICalculationView Members

    public int Numbers1
    {
        get
        {
            return Convert.ToInt32(txtNumber1.Text);
        }
    }

    public int Numbers2
    {
        get
        {
            return Convert.ToInt32(txtNumber2.Text);
        }
    }

    public string Result
    {
        set
        {
            lblResult.Text = value;
        }
    }

    #endregion
    protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {
            m_Presenter.AddNumbers();
        }
        catch (Exception ex)
        {
            if (ExceptionHandleProvider.HandleException(ex, "Global Policy") == true)
            {
                throw ex;
            }
        }      

    }

    public override string Error
    {
        set {pnlError.Visible = true;
            lblException.Text = value; ; }
    }
}