ComAwareEventInfo.RemoveEventHandler(Object, Delegate) Method

Reference

Definition

Namespace:: System.Runtime.InteropServices

Assembly:: System.Runtime.InteropServices.dll

Assembly:: System.Core.dll

Assembly:: netstandard.dll

Source:: ComAwareEventInfo.cs

Source:: ComAwareEventInfo.cs

Source:: ComAwareEventInfo.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Detaches an event handler from a COM object.

public:
 override void RemoveEventHandler(System::Object ^ target, Delegate ^ handler);

public override void RemoveEventHandler (object target, Delegate handler);

[System.Runtime.Versioning.SupportedOSPlatform("windows")]
public override void RemoveEventHandler (object target, Delegate handler);

override this.RemoveEventHandler : obj * Delegate -> unit

[<System.Runtime.Versioning.SupportedOSPlatform("windows")>]
override this.RemoveEventHandler : obj * Delegate -> unit

Public Overrides Sub RemoveEventHandler (target As Object, handler As Delegate)

Parameters

target: Object

The target object that the event delegate is bound to.

handler: Delegate

The event delegate.

Attributes: SupportedOSPlatformAttribute

Exceptions

InvalidOperationException

The event does not have a public remove accessor.

ArgumentException

The handler that was passed in cannot be used.

TargetException

The target parameter is null and the event is not static.

-or-

The EventInfo is not declared on the target.

Note: In .NET for Windows Store apps or the Portable Class Library, catch Exception instead.

MethodAccessException

The caller does not have access permission to the member.

Note: In .NET for Windows Store apps or the Portable Class Library, catch the base class exception, MemberAccessException, instead.

Remarks

This method is similar to the EventInfo.RemoveEventHandler(Object, Delegate) method, except that it allows you to detach events from COM objects.

If target is a COM object, this method releases a delegate to an event by using the ComEventsHelper.Remove(Object, Guid, Int32, Delegate) method.

RemoveEventHandler facilitates unregistering COM event sinks that forward calls to corresponding managed delegates. It requires the following information:

The target object itself (target).
The GUID of the source interface.
The DispID of the method on the COM interface that corresponds to the specified event.
The delegate that would be invoked when the COM object triggers the corresponding event (handler).

RemoveEventHandler looks up the corresponding COM source interface (specified as the first parameter of the ComEventInterfaceAttribute.ComEventInterfaceAttribute(Type, Type) constructor). It then it looks up a method on the source interface whose name is identical to the event name. The value of GuidAttribute on the source interface is the GUID that is passed to ComEventsHelper.Remove(Object, Guid, Int32, Delegate); the value of DispIDAttribute on the method is the DispID value that is passed to ComEventsHelper.Remove(Object, Guid, Int32, Delegate).

Applies to