Here is the second article in the Extension Me series. The Extension Me series focuses on various uses of Extension Methods in .NET and primarily
uses C# as the language of choice. This article will briefly focus on the topic of Asynchronous Programming by extending
System.Action delegates. Using the extension method,
any code wrapped in an instantiation of System.Action delegates can be executed asynchronously. The assumptions made about the reader
are: has experience with the basics of programming in C# and knows what extension methods are. Please be advised: the implications of asynchronous
programming are not to be ignored for severe consequences can occur.
Not only is asynchronous programming fun and beneficial (if used correctly), it is becoming an essential skill as Windows 8 is introduced.
Although the implementation of the following asynchronous pattern is incompatible with Metro-style WinRT apps, the theory of asynchronous programming
will surely be applicable. More information on Asynchronous Programming can be found at Visual Studio Asynchronous Programming
where How-To videos, whitepapers, samples, and walkthroughs are available.
Below is the implementation of the extension method:
public static class ActionExtensions
{
public static void Async(this Action @this)
{
var thread = new Thread(@this.Invoke);
thread.Start();
}
}
The code snippet above shows how extension methods can introduce the beauty of
System.Action
and System.Threading.Thread
objects working together. The Action and the Thread are very close. An essential function of
System.Action is wrapping a block of executable code
while an essential function of System.Threading.Thread is wrapping a block of execution. By embracing these two abilities, code can be executed
asynchronously just by wrapping it in an Action delegate. Here is an example:
public void ReturnsQuick()
{
new Action(() =>
{
}).Async();
}
When the ReturnsQuick method is called, it creates a new instance of an
Action passing a lambda containing “long-running code”.
Using the extension method created previously, the code is executed on a separate thread. The code is now asynchronous and, as the name suggests,
the ReturnsQuick method returns immediately after calling Async().
As mentioned above when introducing the topic of this article, there are plenty of caveats that must be addressed before adopting this approach (especially
application-wide). Shared resource is one of the most important things to consider. If two threads try to access a single resource at the same time, one of them has
to loose! Please take a look at the available PDF, “Threading in C#” by Joseph Albahari
for a more detailed explanation of proper asynchronous approaches.
