2.0 KiB
New (ambiguous) Dispatcher.Invoke overloads could result in different behavior
Scope
Minor
Version Introduced
4.5
Source Analyzer Status
Available
Change Description
The .NET Framework 4.5 adds new overloads to Dispatcher.Invoke that include a parameter of type @System.Action. When existing code is recompiled, compilers may resolve calls to Dispatcher.Invoke methods that have a @System.Delegate parameter as calls to Dispatcher.Invoke methods with an @System.Action parameter. If a call to a Dispatcher.Invoke overload with a @System.Delegate parameter is resolved as a call to a Dispatcher.Invoke overload with an @System.Action parameter, the following differences in behavior may occur:
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If an exception occurs, the xref:System.Windows.Threading.Dispatcher.UnhandledExceptionFilter and xref:System.Windows.Threading.Dispatcher.UnhandledException events are not raised. Instead, exceptions are handled by the xref:System.Threading.Tasks.TaskScheduler.UnobservedTaskException?displayProperty=name event.
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Calls to some members, such as xref:System.Windows.Threading.DispatcherOperation.Result, block until the operation has completed.
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Quirked
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Build-time break
Recommended Action
To avoid ambiguity (and potential differences in exception handling or blocking behaviors), code calling Dispatcher.Invoke can pass an empty object[] as a second parameter to the Invoke call to be sure of resolving to the .NET 4.0 method overload.
Affected APIs
M:System.Windows.Threading.Dispatcher.Invoke(System.Delegate,System.Object[])M:System.Windows.Threading.Dispatcher.Invoke(System.Delegate,System.TimeSpan,System.Object[])M:System.Windows.Threading.Dispatcher.Invoke(System.Delegate,System.TimeSpan,System.Windows.Threading.DispatcherPriority,System.Object[])M:System.Windows.Threading.Dispatcher.Invoke(System.Delegate,System.Windows.Threading.DispatcherPriority,System.Object[])
Category
Windows Workflow Foundation (WF)