This document discusses code weaving and the Fody tool. It begins with an introduction to code weaving, which involves generating additional code at compile-time to implement aspects like adding boilerplate code, aspect-oriented programming, and obfuscation. It then discusses how code weaving can be done through techniques like emitting MSIL, using reflection, dynamic proxies, and aspect-oriented programming tools. The bulk of the document focuses on Fody, which is a code weaving library that uses Mono.Cecil and integrates with the build process. It describes many pre-built weavers available on NuGet and demonstrates how to write a custom weaver. It also covers some gotchas and provides additional resources.

1. {{
FodyFody
code weaving made funcode weaving made fun

2. About meAbout me
 Tomasz PluskiewiczTomasz Pluskiewicz
 WrocławWrocław
 MakoLab S.A.MakoLab S.A.
 @tpluscode@tpluscode

3.  About code weavingAbout code weaving
 About FodyAbout Fody
 ExamplesExamples
 QuestionsQuestions
AgendaAgenda

4. „„Generate” additional code to:Generate” additional code to:
 Add boilerplate code automaticallyAdd boilerplate code automatically
 Implement Aspect-Oriented ProgrammingImplement Aspect-Oriented Programming
 ObfuscationObfuscation
 Build killer APIsBuild killer APIs
What is code weaving?What is code weaving?

5.  Source code weavingSource code weaving
 Compile-time weavingCompile-time weaving
 Runtime weavingRuntime weaving
How can I weave?How can I weave?

6.  Emitting MSILEmitting MSIL
 Refelction.EmitRefelction.Emit
 Mono.CecilMono.Cecil
 Dynamic proxiesDynamic proxies
 Castle, LinFu, Unity, Impromptu InterfaceCastle, LinFu, Unity, Impromptu Interface
 AOPAOP
 PostSharp, AfterthoughtPostSharp, Afterthought
 RoslynRoslyn
The toolsThe tools

7.  Simple but less flexibileSimple but less flexibile
 Requires runtime reference to PostSharpRequires runtime reference to PostSharp
 Requires Visual Studio extensionRequires Visual Studio extension
 Aspects in embedded resourcesAspects in embedded resources
 Full functionality is not freeFull functionality is not free
PostSharpPostSharp

8. IL weaving (with Cecil)IL weaving (with Cecil)
 ILIL isis difficultdifficult
 Need to update PDBsNeed to update PDBs
 MSBuild integrationMSBuild integration

9. Fodies are small passerine
birds belonging to the genus
Foudia in the weaver family
Ploceidae
- wikipedia/Fody

10. WeaverWeaver
CodeCode

11.  Many pre-built weaversMany pre-built weavers
 Uses Mono.CecilUses Mono.Cecil
 Integrates into build processIntegrates into build process
 Works on build serversWorks on build servers
 Leaves no referencesLeaves no references
 Well… depending on the pluginWell… depending on the plugin
 Versatile:Versatile:
 .NET 3.5-4.5.NET 3.5-4.5
 Silverlight 4 & 5Silverlight 4 & 5
 Mono, MonoTouch, MonoDroidMono, MonoTouch, MonoDroid
 Windows Phone 7 & 8 (also Metro)Windows Phone 7 & 8 (also Metro)
 Portable Class LibraryPortable Class Library
FodyFody

12.  Almost 70 packages on NuGetAlmost 70 packages on NuGet
 NullGuardNullGuard
 PropertyChangedPropertyChanged
 CosturaCostura
 AnotarAnotar
 ModuleInitModuleInit
 FreezableFreezable
 MethodDecoratorMethodDecorator
 InfoOfInfoOf
 ToStringToString
Community weaversCommunity weavers

13. DemoDemo

14.  Emitting IL is still required (duh!)Emitting IL is still required (duh!)
 However FodyHowever Fody
 Injects weavers to build pipelineInjects weavers to build pipeline
 Loads assembliesLoads assemblies
 Rewrites PDBsRewrites PDBs
 Reapplies strong nameReapplies strong name
 Writes to MSBuild build logWrites to MSBuild build log
Custom weavingCustom weaving

15.  Assembly with .Fody suffixAssembly with .Fody suffix
 ILMerge referencesILMerge references
 Pulic ModuleWeaver classPulic ModuleWeaver class
 Mutltiple deployment optionsMutltiple deployment options
 In-solutionIn-solution
 $(SolutionDir)/Tools
 NuGet packageNuGet package
 Learn fromLearn from
 existing weavers (example follows)existing weavers (example follows)
 Fody wikiFody wiki
Writing a weaverWriting a weaver

16. DemoDemo

17.  Don’t use Visual Studio pluginDon’t use Visual Studio plugin
 Weaver order sometimes does matterWeaver order sometimes does matter
 Debugging unavailable codeDebugging unavailable code

 LogInfo requires detailed MSBuild outputLogInfo requires detailed MSBuild output
 Tools -> Projects and Solutions -> Build andTools -> Projects and Solutions -> Build and
RunRun
 Remember to update Fody packageRemember to update Fody package
GotchasGotchas

18.  https://github.com/Fody/https://github.com/Fody/
 https://github.com/Fody/Fody/wiki/HowToWriteAnAddinhttps://github.com/Fody/Fody/wiki/HowToWriteAnAddin
 https://github.com/Fody/Fody/wiki/ModuleWeaverhttps://github.com/Fody/Fody/wiki/ModuleWeaver
 https://github.com/Fody/Fody/wiki/DeployingAddinsAsNugetshttps://github.com/Fody/Fody/wiki/DeployingAddinsAsNugets
 http://www.planetgeek.ch/2013/08/31/dont-wear-woven-sweatshirts-instead-weave-your-http://www.planetgeek.ch/2013/08/31/dont-wear-woven-sweatshirts-instead-weave-your-
assemblies/assemblies/
 http://haacked.com/archive/2013/01/04/mitigate-the-billion-dollar-mistake-with-aspects.aspx/http://haacked.com/archive/2013/01/04/mitigate-the-billion-dollar-mistake-with-aspects.aspx/
LinksLinks

19. Questions?Questions?

21. The end – wake up nowThe end – wake up now 