Adding aspect to an abstract method?

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Adding aspect to an abstract method?

PostSharp gives this error:

PostSharp: Cannot apply an OnMethodInvocation aspect (...) with target-site weaving on the abstract or external method "...". Consider excluding the aspect from this method or use call-site weaving.

Suggested call-site weaving is not an appropriate solution for me. Is there any way to add pre/post processing for the abstract method?

This is of course imposible - how would you perform target-site weaving with an abstract method, a method without any code? You can of course perform target-site weaving with all derived types implementing the method, but this requires that you control this types. Or you could make the method non-abstract and virtual and require derived types to call the base implementation.

Daniel Brückner 2009-09-15 09:53:50

There is at least one way to make it possible - use "template method" pattern. PostSharp already uses it for virtual methods. The same can be done with abstract methods.

skevar7 2009-09-15 10:22:18

"[...] way to add pre/post processing for the abstract method?" Do you mean performing some steps before or after a call in code? And what do you want to achieve with the aspect?

Daniel Brückner 2009-09-15 10:32:22

I just need to perform some code before and after each method from the specified group of methods. PostSharp seemed a good solution, but problem with abstract methods makes it impossible.

skevar7 2009-09-15 10:40:46

+1 A:

I suggest you use aspect inheritance. The aspect will be automatically added to all methods implementing the abstract method.

See MulticastAttribute.AttributeInheritance or MulticastAttributeUsageAttribute.Inheritance, or official documentation for details.

Gael Fraiteur 2009-09-15 11:04:33

Looks like what I need, but it doesn't work correctly with OnMethodInvocation aspect. Any ideas? BTW, your documentation behaves very oddly in Opera browser.

skevar7 2009-09-15 15:49:56

OnMethodInvocation should work even with inheritance. Check with Reflector to understand what happens.

Gael Fraiteur 2009-09-16 14:17:28

It shows compile-time error for this aspect ;)

skevar7 2009-09-18 05:15:00

ansaurus

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