CODEWITHSUNDEEP
c#.netasynchronoustaskasync-await
DevonTaig
DevonTaig

Reputation: 711

Call method which accepts an Action parameter synchronously

I am working with a library for which I do not have the source, and as such I can't decorate it with the async keyword and do things like await a Task (at least I don't know how to do that). It exposes a method which returns an object (I'll call it "answer") and takes an integer, and a parameter of type Action where I retrieve that answer. How can I wait for answer to get populated before my code continues?

Object answer = null;
remoteLibrary.remoteMethod(42, x => 
{
  answer = x.Value; //This might take a few seconds
});
//I want to do something here with "answer" AFTER it has been populated

Upvotes: 1

Views: 48

Answers (1)

i3arnon
i3arnon

Reputation: 116676

You need a synchronization construct. And since this can take a few seconds it would be a waste to use a synchronous (blocking) one so I suggest an asynchronous one like TaskCompletionSource:

var tcs = new TaskCompletionSource<object>();
remoteLibrary.remoteMethod(42, x => 
{
    tcs.SetResult(x.Value);
});

var answer = await tcs.Task;
// use answer

The TaskCompletionSource exposes a task that you can await that wouldn't complete until you call SetResult (or SetCanceled, SetException). When it completes you get the result you set in SetResult so you don't need the dummy variable anymore.

Upvotes: 2

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