C#: Partial methods and Action, non implemented body

Question

I want to call a partial method from outside of the declaring class. This is not allowed as partial methods are implicitly private. You can not set a delegate to point to a partial so I am proposing the following:

  public partial class MyClass  {

      AnotherClass _anotherClass;

      public MyClass  () {
         _anotherClass = new AnotherClass();
         _anotherClass.Method = new Action(() => {            
            this.Method(); 
         });
      }

      partial void Method();

      //sometimes this method will be implemented
      //partial void Method() {
         //do something
      //}
   }

   public class AnotherClass {

      public Action Method { get; set;}

      public void SomeOtherMethod(){
         this.Method();
      }
   }

The classes are tightly coupled, they are in a parent child relationship. I want the parent to have a method that it can override to know about property changes on the child. I could attach event handlers to each of the children however the child already knows about its parent so having the child inform the parent directly seems like the way to go. Except when the parent does not care which is why I want to be able to implement a partial if I do care. This question is basically about ease of programming vs performance. I know I could attach event handlers only to the situation where I do care, but with the implementation as above I can generate all the partial methods and only implement the partials if I care.

My question relates to the times that the partial method Method() is not implemented. When the Action method is called will the compiler optimise it away as its body is empty? If I get a heap of these Action calls being made could I suffer a performance penalty? Is there a better way to get the same functionality?

You are not going to get a noticeable performance hit, calling an empty Action is a pretty cheap operation. I doubt the compiler will stub away the void Action. — Sam Saffron, Dec 17 '10 at 00:33
I dont get why peope talk abotu performance. If it matters ... MEASURE IT ;) — John Nicholas, Mar 22 '11 at 09:44

score 3 · Accepted Answer · answered Dec 17 '10 at 04:20

3

Per, MSDN (emphasis added):

One part of the class contains the signature of the method. An optional implementation may be defined in the same part or another part. If the implementation is not supplied, then the method and all calls to the method are removed at compile time.

Thus, no real penalty as the calls are optimized away.

answered Dec 17 '10 at 04:20

Jay

56,361
10
99
123

yes but the partial method call is inside an Action that will be called (it just won't have a body) so there must be some processing involved. – Aran Mulholland Dec 17 '10 at 06:24
An `Action` is a void method. The processing is equivalent to calling a method with no body. I know that JIT omits calls to empty methods, but even if it didn't do so for the 'Action', the call won't impact performance in any measurable way. – Jay Dec 17 '10 at 13:03

score 0 · Answer 2 · answered Dec 17 '10 at 04:53

The performance difference between the different scenarios you propose will be sub-millisecond. I would go with the most maintainable solution rather than trying to optimize for performance at such a low level.

So, I would go with the event solution because I think other .NET developers who work on the code after you would be more familiar with the solution rather than the exotic partial method approach which you present.

C#: Partial methods and Action, non implemented body

2 Answers2