Raises a user-supplied exception if an asynchronous operation failed.
Assembly: System (in System.dll)
If you have derived your own class from the AsyncCompletedEventArgs class, your read-only properties should call the method before they return the property value. If the component's asynchronous worker code assigns an exception to the Error property or sets the Cancelled property to true, the property will raise an exception if a client tries to read its value. This prevents clients from accessing properties that are potentially not valid because of a failure in the asynchronous operation.
The following code example demonstrates how to use in derived class properties. This code example is part of a larger example provided for the System.ComponentModel.AsyncOperationManager class.
' Define a custom Completed-event arguments class allowing ' the data gathered by GetPersons to be returned. Public Class GetPersonsCompletedEventArgs Inherits AsyncCompletedEventArgs Private m_dataListValue As List(Of Person) Public Sub New _ (ByVal dataList As List(Of Person), _ ByVal exception As Exception, _ ByVal cancelled As Boolean, _ ByVal userState As Object) MyBase.New(exception, cancelled, userState) m_dataListValue = dataList End Sub Public ReadOnly Property DataListValue() As List(Of Person) Get Me.RaiseExceptionIfNecessary() Return m_dataListValue End Get End Property End Class
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.