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DependencyObject.AddHandler Method

Adds a handler for an event of a DependencyObject.

Namespace:  System.Workflow.ComponentModel
Assembly:  System.Workflow.ComponentModel (in System.Workflow.ComponentModel.dll)

public void AddHandler(
	DependencyProperty dependencyEvent,
	Object value


Type: System.Workflow.ComponentModel.DependencyProperty
The DependencyProperty.
Type: System.Object
The Object that represents the value of this property. In this case, a Delegate type.


Either of the arguments is a null reference (Nothing in Visual Basic).


Value is of incorrect Type.


The dependencyEvent represents a non-event DependencyProperty.

When you create a delegate, you identify the method that handles the event. To associate the event with your event handler, add an instance of the delegate to the event. Unless you remove the delegate, the event handler is called whenever the event occurs. Multiple delegates can be added to handle an event. For more information about event-handler delegates, see Events and Delegates.

Handlers are added and removed using the following code. This code example is part of the Send E-mail SDK sample and is from the SendMailActivity.cs file. For more information, see Send E-mail Activity Sample.

        #region Public Events

        [Description("The SendingEmail event is raised before an email is sent through SMTP.")]
        public event EventHandler SendingEmail
                base.AddHandler(SendEmailActivity.SendingEmailEvent, value);
                base.RemoveHandler(SendEmailActivity.SendingEmailEvent, value);

.NET Framework

Supported in: 4, 3.5, 3.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.