Creating a method to return Task<List<MyDataObject>> foo()

Question

I can solve this in .Net 4.5 but I must solve it in .Net 4.0, and so far i have not been successful. I have not been able to get my replies into a Task<List<MyDataObject>>. The code below can create List<MyDataObject>.

public Task<List<MyDataObject>> Foo()
{
     IEnumerable<string> names = GetList();
     var tasks = new List<Task>();
     foreach (var name in names)
     {               tasks.Add(Task<MyDataObject>.Factory.StartNew(
               () =>
               {
                    var reply = new MyDataObject();
                    var workerObject = new WorkerObject();
                    workerObject.Foo2();
                    reply.Success = true;
                    return reply;
                }));
       }

       Task.WaitAll(tasks.ToArray());
       var replyList = new List<MyDataObject>();
       for (int i = 0; i < tasks.Count(); i++)
       {     replyList.Add(((Task<MyDataObject>)tasks[i]).Result);
        }

        return replyList;
}

WhenAll() is 4.5 only

await is 4.5 only

so i cannot accept those

I agree that this doesnt compile. What I showed was i can iterate through the results. However I do not know how to go from

List<MyDataObject>()

to

Task<List<MyDataObject>>

Thank you for the replies. I am going to accept Yuval Itzchakov's answer because it solves my problem in a simple manner. I am limited to no new assemblies for this use case. I would have selected 280Z28's second option had I had another method that required this functionality.

Answer 1

Use a TaskCompletionSource<List<MyDataObject>>

Task.WaitAll(tasks.ToArray());

var replyList = new List<MyDataObject>();

for (int i = 0; i < tasks.Count(); i++)
{                
    replyList.Add(((Task<MyDataObject>)tasks[i]).Result);
}

var tcs = new TaskCompletionSource<List<MyDataObject>>();
tcs.SetResult(replyList);
return tcs.Task;

You can also download Microsoft.Bcl.Async to get the NET 4.5 effect in .NET 4.0