Question

I’ve used async methods today, calling methods asynchronously and using the caller’s callback methods.

Recently, I can across this post which talks about the new way to do this using the new await keyword. Other than saving few lines of code, what are the main advantages of this new model?

Does it offer a built in solution for when you make two different async calls but want the control to return to only one of the caller’s callback, after both have completed?

What does CTP (Community Technical Preview) mean? Is this new keyword available in next version of C# and VB.NET?

Answer 1

From Eric Lippert’s Blog post Asynchrony in C# 5, Part One

The designers of C# 5.0 realized that
writing asynchronous code is painful,
in so many ways. Asynchronous code is
hard to reason about, and as we’ve
seen, the transformation into a
continuation is complex and leads to
code replete with mechanisms that
obscure the meaning of the code.

As the article explains like iterator blocks, anonymous methods, query comprehensions and dynamic types the intent is to make something that is hard, easy.

As for Community Technical Preview bit. Typically it means that “await” will be in the next version of C#, but there’s no guarantee that something about it won’t change. So if you write something (code or blog posts) and its breaks don’t blame them.