Asynchronous method invocation: Difference between revisions

Revision as of 16:06, 9 October 2008

Revision as of 16:13, 9 October 2008

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TheIn computer software, the '''Asynchronousasynchronous error reporting''' [[design pattern]] decouples exception throwing from theirthe origin of the exception to the use of the result, in such a way that exceptions happen in a "safe" way. Often used in connection with the [[Activeactive Objectobject]] pattern.<ref> [http://msdn.microsoft.com/en-us/library/ms228974(VS.80).aspx "Best Practices for Implementing the Event-based Asynchronous Pattern"] Under Errors and Exceptions</ref>

==Notes==

Recently seen implemented as a basic principle in [[Microsoft .NET]].<ref> [http://msdn.microsoft.com/en-us/library/ms228974(VS.80).aspx "Best Practices for Implementing the Event-based Asynchronous Pattern"] Under Errors and Exceptions</ref>

<references/>

== C# example ==

{{uncat}}

<source lang="csharp">

public class SomethingCallbackResult

{

private object _result;

public object Result {

get {

//Exception is not thrown until we ask for result

if (_result is Exception)

throw (Exception)_result;

return _result;

}

set {

_result = value;

}

}

}

public class Something

{

public delegate void SomethingCallback(SomethingCallbackResult result);

public void BeginSomething(SomethingCallback callback)

{

//Start thread with worker

//return

}

private void worker(SomethingCallback callback)

{

SomethingCallbackResult result = new SomethingCallbackResult();

try

{

//... Actual work ...

result.Result = ...

}

catch (Exception e)

{

//Exception is not throw here, but just saved for later use

result.Result = e;

}

callback(result);

}

}

</source>

==Notes==

<references/>