Aspect oriented programming
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This document discusses aspect-oriented programming (AOP) and how it can be implemented using PostSharp. AOP aims to make cross-cutting concerns like logging and error handling easier to implement separately from business logic. It describes how PostSharp uses IL weaving to modify code at compile time or JIT to add aspects without changing the original code. Alternatives to PostSharp include using the .NET profiler API or proxies, but IL weaving generally has better performance. The document also briefly outlines how AOP may be improved in future versions of C# compilers like Roslyn.
Aspect oriented programming
- 2. AgendaWhat, when, why of AOP?How is it implemented in PostSharp and how does it work?Alternatives to PostSharpLooking to the futureDiscussion
- 3. Every project has “boring” codesource: Microsoft Application Architecture Guide, 2nd Edition
- 4. AOP DetailsGoal to make cross cutting concerns easy to implement and focus on business codeXerox PARC in 2001AspectJMany implementations now daysAKA: AOSD
- 5. Scenario code – simple prime calculatorCustomer says it’s wrong. We need logging to diagnose…
- 6. Let’s add logging – trace input & outputEasy to miss some placesLots of repetition of codeNeed to teach thisNot portable5 extra lines of code
- 7. What about some procedural help?Not junior friendlyNeed 1 per signature15 extra lines of code
- 8. So how does aspects solve that?Feel like you are missing something?1 extra line of code
- 9. Demo time…
- 10. Under the hoodSource: .NET Reflector 6.8IL modified
- 11. Many ways to implement AOP in .NET currentlyPopular: IL Weaving @ compile or JITPostSharp & Mono.CecilLess:Hooking into .NET profiler APIProxies
- 12. IL Weaving.cs or .vb codeIL (pure)PostSharpIL (Merged)
- 13. Hooking the profilerDisadvantagesPoor performance
- 15. Not designed for thisAdvantagesNothing is safe from it’s power
- 16. Solves some fringe cases (i.e. mocking static methods)ApplicationCOM APICLRProfilerEnvironmental
- 17. ProxiesProxiedNormalMethod CallMethod CallProxyObjectDisadvantagesComplex with ContextBoundObject
- 18. Perf is worse than IL weavingAdvantagesUsing DI it can be easier
- 19. Perf is better than .NET profilerObject
- 20. Future: Post Roslyn TheoryRoslynNext version of C#/VB “compiler”Written in managed codeAvailable as a servicePost RoslynInsert new language semantics Approach the AspectJ style
- 21. SummaryAOPWay to untangle cross cutting concerns out of business codeGreat re-useCan be easy to use (depending on implementation)Many options to do this!