'System.Threading.Tasks.Task' does not contain a definition for 'WhenAny'_

Question

Hi All,

I have copied the below code from the document "The Task-based Asynchronous Pattern"

var recommendations = new List<Task<bool>>() 
{ 
    GetBuyRecommendation1Async(symbol), 
    GetBuyRecommendation2Async(symbol),
    GetBuyRecommendation3Async(symbol)
};
Task<bool> recommendation = await Task.WhenAny(recommendations);
if (await recommendation) BuyStock(symbol);

And when I compiled, I get the above mentioned error. What would have went wrong?

Thanks for reading

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Answer 1

What version of .NET 4 are you using?  WhenAny was added to Task in .NET 4.5.  If instead you're using .NET 4 with the Async CTP, you need to use TaskEx.WhenAny rather than Task.WhenAny.

Answer 2

Stephen,

Thanks for the reply. As a matter of fact, I'm using framework 4.0, thus, the issue. But the document written by you, doesn't specify about this. Please add this.

FYI, in the mentioned document, you have made it clear about Task.Delay is added to framework 4.5. Hence, it would be great if you modify the same document with all the new things added to framework 4.5 when compared to 4.0.

Regards

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Every thing is perfect as long as you share