/V4/StockTrader RI/Silverlight/StockTraderRI.Infrastructure.Silverlight/DependencyPropertyHelper.cs

//===================================================================================

// Microsoft patterns & practices

// Composite Application Guidance for Windows Presentation Foundation and Silverlight

//===================================================================================

// Copyright (c) Microsoft Corporation.  All rights reserved.

// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY

// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT

// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

// FITNESS FOR A PARTICULAR PURPOSE.

//===================================================================================

// The example companies, organizations, products, domain names,

// e-mail addresses, logos, people, places, and events depicted

// herein are fictitious.  No association with any real company,

// organization, product, domain name, email address, logo, person,

// places, or events is intended or should be inferred.

//===================================================================================

using System.Windows;

using System;



namespace StockTraderRI.Infrastructure

{

    /// <summary>

    /// Defines helper methods for dependency properties.

    /// </summary>

    public static class DependencyPropertyHelper

    {

        /// <summary>

        /// Gets or, if it is not defined sets, the <paramref name="property"/> value on the <paramref name="dependencyObject"/> object.

        /// </summary>

        /// <typeparam name="T"><see cref="System.Type"/> of the <see cref="DependencyProperty"/>.</typeparam>

        /// <param name="dependencyObject">Object on which the <paramref name="property"/> is set.</param>

        /// <param name="property">Property whose value will be retrieved.</param>

        /// <returns>Value of <paramref name="property"/> on <paramref name="dependencyObject"/>.</returns>

        public static T GetOrAddValue<T>(DependencyObject dependencyObject, DependencyProperty property) where T : class, new()

        {

            if (dependencyObject == null)

            {

                throw new ArgumentNullException("dependencyObject");

            }



            T value = dependencyObject.GetValue(property) as T;

            if (value == null)

            {

                value = new T();

                dependencyObject.SetValue(property, value);

            }



            return value;

        }

    }

}