Too many arguments in BeginXXX for FromAsync?

Question

I have an async method with the following signature:

IAsyncResult BeginGetMyNumber(string foo, string bar, string bat, int bam, AsyncCallback callback, object s         


        

Answer 1

Yeah, basically, you've run out of arguments. :(

The FromAsync method only takes a maximum of three passed-to-the-async-call arguments, spelled out in full like so:

var result  = Task
    .Factory
    .FromAsync(
        BeginGetMyNumber,
        EndGetMyNumber,
        "foo",
        "bar",
        "bat",
        null);

Which would work if you had:

IAsyncResult BeginGetMyNumber(
   string foo, 
   string bar, 
   string bat, 
   AsyncCallback callback, 
   object state)
{
}

But ye've got one too many.

Ooh, got something that might help - you WILL want to clean this up, this is extremely thrown-together!!!

public static class Ext
{
    public static Task FromAsync(
        this TaskFactory factory,
        Func beginMethod, 
        Func endMethod, 
        TArg1 arg1,
        TArg2 arg2,
        TArg3 arg3,
        TArg4 arg4,
        object state,
        TaskCreationOptions creationOptions = TaskCreationOptions.None, 
        TaskScheduler scheduler = null)
    {
        scheduler = scheduler ?? TaskScheduler.Current;
        AsyncCallback callback = null;
        if (beginMethod == null)
        {
            throw new ArgumentNullException("beginMethod");
        }
        if (endMethod == null)
        {
            throw new ArgumentNullException("endMethod");
        }
        TaskCompletionSource tcs = 
             new TaskCompletionSource(state, creationOptions);
        try
        {
            if (callback == null)
            {
                callback = delegate (IAsyncResult iar) 
                {
                    tcs.TrySetResult(endMethod(iar));
                };
            }
            beginMethod(arg1, arg2, arg3, arg4, callback, state);
        }
        catch
        {
            tcs.TrySetResult(default(TResult));
            throw;
        }
        return tcs.Task;
    } 
}