DependencyObject.RemoveHandler Method (System.Workflow.ComponentModel)

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.NET Framework Class Library

DependencyObject.RemoveHandler Method

Removes an EventHandler from an associated DependencyProperty.

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

Syntax

Visual Basic

Public Sub RemoveHandler ( _
	dependencyEvent As DependencyProperty, _
	value As Object _
)

public void RemoveHandler(
	DependencyProperty dependencyEvent,
	Object value
)

Visual C++

public:
void RemoveHandler(
	DependencyProperty^ dependencyEvent, 
	Object^ value
)

member RemoveHandler : 
        dependencyEvent:DependencyProperty * 
        value:Object -> unit

Parameters

dependencyEvent: Type: System.Workflow.ComponentModel.DependencyProperty
The DependencyProperty.

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

Exceptions

Exception	Condition
ArgumentNullException	Either of the arguments is a null reference (Nothing in Visual Basic).
ArgumentException	The dependencyEvent is a metaproperty.
ArgumentException	The dependencyEvent is not an event.
ReadOnlyException	The value is a ActivityBind and this instance is not in DesignMode.

Remarks

Provided as a convenient direct method for removing an event delegate.

When you create a delegate, you identify the method that will handle 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. For more information about event-handler delegates, see Events and Delegates.

Examples

Handlers are added and removed using the following code. For more information, see Send E-mail Activity Sample.

Visual Basic



#Region "Public Events"

        <DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)> _
        <Description("The SendingEmail event is raised before an email is sent through SMTP.")> _
        <Category(EventsCategory)> _
        <Browsable(True)> _
        Public Custom Event SendingEmail As EventHandler
            AddHandler(ByVal value As EventHandler)
                MyBase.AddHandler(SendEmailActivity.SendingEmailEvent, value)
            End AddHandler

            RemoveHandler(ByVal value As EventHandler)
                MyBase.RemoveHandler(SendEmailActivity.SendingEmailEvent, value)
            End RemoveHandler

            RaiseEvent(ByVal sender As Object, ByVal e As System.EventArgs)

            End RaiseEvent
        End Event


        #region Public Events

        [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        [Description("The SendingEmail event is raised before an email is sent through SMTP.")]
        [Category(EventsCategory)]
        [Browsable(true)]
        public event EventHandler SendingEmail
        {
            add
            {
                base.AddHandler(SendEmailActivity.SendingEmailEvent, value);
            }
            remove
            {
                base.RemoveHandler(SendEmailActivity.SendingEmailEvent, value);
            }
        }

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Security

Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

Platforms

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.

Reference

DependencyObject Class

System.Workflow.ComponentModel Namespace