What's TaskCompletionSource good for?

We can completely avoid TaskCompletionSource though if are able to call a method with await.

For example this method tries to get a value from a cache before resorting to doing an actual async operation:

        private async static Task<IPAddress[]> resolve(string domain)
        {
            if (cache.ContainsKey(domain))
               return(cache[domain]);

            IPAddress[] result = await Dns.GetHostAddressesAsync(domain);

            cache.TryAdd(domain,result);

            return (result);
        }

This gives us the same effect - namely allows us to control how a Task completes (and thus setting its result from a cached value) yet has no need for TaskCompletionSource.

So - it seems to me that we have no more need for TaskCompletionSource with C# 5 - we can achieve the same effect in other ways...

Cap'n