/CBR/CBR.Core/Helpers/MVVM/Events/WeakAction.cs

// ****************************************************************************

// <copyright file="WeakAction.cs" company="GalaSoft Laurent Bugnion">

// Copyright © GalaSoft Laurent Bugnion 2009-2011

// </copyright>

// ****************************************************************************

// <author>Laurent Bugnion</author>

// <email>laurent@galasoft.ch</email>

// <date>18.9.2009</date>

// <project>GalaSoft.MvvmLight</project>

// <web>http://www.galasoft.ch</web>

// <license>

// See license.txt in this solution or http://www.galasoft.ch/license_MIT.txt

// </license>

// ****************************************************************************



using System;



namespace CBR.Core.Helpers

{

    /// <summary>

    /// Stores an <see cref="Action" /> without causing a hard reference

    /// to be created to the Action's owner. The owner can be garbage collected at any time.

    /// </summary>

    ////[ClassInfo(typeof(Messenger))]

    public class WeakAction

    {

        private readonly Action _action;



        private WeakReference _reference;



        /// <summary>

        /// Initializes a new instance of the <see cref="WeakAction" /> class.

        /// </summary>

        /// <param name="target">The action's owner.</param>

        /// <param name="action">The action that will be associated to this instance.</param>

        public WeakAction(object target, Action action)

        {

            _reference = new WeakReference(target);

            _action = action;

        }



        /// <summary>

        /// Gets the Action associated to this instance.

        /// </summary>

        public Action Action

        {

            get

            {

                return _action;

            }

        }



        /// <summary>

        /// Gets a value indicating whether the Action's owner is still alive, or if it was collected

        /// by the Garbage Collector already.

        /// </summary>

        public bool IsAlive

        {

            get

            {

                if (_reference == null)

                {

                    return false;

                }



                return _reference.IsAlive;

            }

        }



        /// <summary>

        /// Gets the Action's owner. This object is stored as a <see cref="WeakReference" />.

        /// </summary>

        public object Target

        {

            get

            {

                if (_reference == null)

                {

                    return null;

                }



                return _reference.Target;

            }

        }



        /// <summary>

        /// Executes the action. This only happens if the action's owner

        /// is still alive.

        /// </summary>

        public void Execute()

        {

            if (_action != null

                && IsAlive)

            {

                _action();

            }

        }



        /// <summary>

        /// Sets the reference that this instance stores to null.

        /// </summary>

        public void MarkForDeletion()

        {

            _reference = null;

        }

    }

}