Sunday, April 27, 2008

Extensions methods... Still missing some features

I like extension methods in dotNet. Extension methods give you easier access to your helper and util classes with static methods that operate on your object. It's not that extension methods give you any new features, they just give a little different syntax that might be a little more natural. It gives the programmer a way to use methods across your project without learning the syntax of your helper classes.

I like extension methods because they give me a way of separating my code where I find it fit, and still give the user a feal of coherence. Extension methods do not affect the architecture of your application as it doesn't change where code is, just the syntax of accessing it.

So far I have found 3 areas where extension methods fall short.

1. :
Extension methods can be made work like instance methods. Extension method cannot be used as static methods. In a static context they could have been great for factory methods and such for your classes and interfaces.
IDomainObject o = IDomainObject.Load(1); //Working on the type. Can't be implemented as an Extension method
o.Save(); //working on an instance. This is ok
Wouldn't static extension methods be cool? :)

2.: Extension methods can't overload operators. As I generally dislike operator overlodings, this is not a big problem for me. I do however have one place in mind where I could use this.

3.: Visual studio does not recognice Extension methods if your code is in the class that is extended.
public class Test{
public void doStuff(){
HandleMe(); //Can't be implemented through extension methods
this.HandleMe2(); //This can be an extension method.

I don't really see why this is not implemented. Maybe it will come in a future release.

Extension methods are GREAT!


  1. Another cool application of an extension method is this "fallback" ToString() implemention:

  2. thanks ronnie... that looks cool!