Community Tech Days C# 4.0
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C# 4.0 introduced several new language features including dynamic typing using the dynamic keyword, optional and named parameters, covariance and contravariance in generics, and improved COM interoperability. The presentation provided an overview of these features and their benefits, demonstrated examples, and discussed how the Dynamic Language Runtime enables dynamic typing in C#.
Community Tech Days C# 4.0
- 1. C# 4.0 Language EnhancementsSankarsan Bose11th October 2009
- 2. Agenda Journey of C#
- 4. C# 4.0 Features
- 6. Named And Optional Parameters
- 7. Covariance And Contravariance
- 8. Improved COM InterOp Journey of C#???Functional + LINQGenericsStatic Language + Managed Code
- 10. C# 4.0 Features Dynamic Programming
- 11. Optional and Named Parameters
- 12. Co- and Contra-variance
- 13. Improved COM Interoperability Dynamic ProgrammingRuby Code Sample No type is defined
- 14. Stores string value
- 15. “+” operator concatenates
- 17. “+” operator addsType Determined At Runtime Based On Type Of Value Stored
- 18. Dynamic ProgrammingRuby Code Sample Both classes define “print”
- 19. Exactly same signature
- 20. No type defined for parameter “p”
- 21. Any object supporting method “print” is a valid input
- 22. This is called “Duck Typing”Method To Be Invoked Is Decided At Runtime
- 23. Dynamic ProgrammingDynamic Method Dispatch in C# (Before 4.0)Both are staticallytyped as IOfficeDocument
- 24. Dynamic ProgrammingDynamically Typed Objects in C# 4.0 New keyword “dynamic”
- 25. Statically Typed as “dynamic”
- 26. Actual type determined at runtimeDynamic Method Invocation
- 27. Dynamic ProgrammingPros No risk of brittle class hierarchy
- 28. Need not implement all methods of interface
- 29. More flexible , highly productiveCons Developer needs thorough understanding of codebase
- 30. Misuse might lead to poor maintainabilityDynamic ProgrammingDemo
- 31. Dynamic ProgrammingC# is a statically typedlanguageHow we are making it dynamic ???Here Comes DLRDynamic Language Runtime
- 32. Dynamic ProgrammingDLR is additional libraries to fit the dynamic languages into the CLR Store program/code as data
- 33. Caching mechanism for dynamic call
- 34. Provide language specific supportDynamic ProgrammingClass Generated Under The Hood CallSite is created before method call
- 35. Actual method call is delegated to CallSite
- 36. Compiler Generated Class
- 37. Reference to CallSiteDynamic ProgrammingCLR – DLR InteractionRuntimeCompile TimeCLRCompiler injects call to DLR CallSite C# Source CodeMSIL CodeCall is delegated to DLR Call Site CacheDLRCallSite CacheDetermines type Determines methodReturns Expression TreeCall Runtime Binder for Cache missC# Runtime Binder
- 38. Optional & Named Parameters“b” & “c” are nullable & optional Calling code has to pass null value This is an issue for large no of parameters
- 39. Optional & Named ParametersSolution Using Overload in C# (Before 4.0)One overload accepts only “a”Another accepts “a” & “b”This is not possibleSignature clash with the previous method
- 40. Optional & Named ParametersSolution Using C# 4.0Optional Parameter with Default ValueOptional Parameter omitted in the callMethod call with parameter namesPosition reversed
- 41. Optional & Named ParametersDemo
- 42. Covariance & ContravarianceSubclassEllipseCircleAs per Liskov Substitution Principle(LSP):Any program which expects an object of EllipseWill function without any change with an object of CircleCovariance – Type substitution as per LSPContravariance – Type substitution reverse to LSP
- 43. Covariance & ContravarianceDelegate Covariance in C# (Already Present)Func<Base> is a delegate which returns type “Base”Func<Base> can be replaced by function with return type “Derived”
- 44. Covariance & ContravarianceDelegate Contravariance in C# (Already Present)Func<Derived , Object> is a delegate which accepts type “Derived”Func<Base> can be replaced by function which accepts type “Base”
- 45. Covariance & ContravarianceCovariance in Arrays (Existing in C# )This covariance is allowedThis code compilesBut throws Runtime Exception
- 46. Covariance & ContravarianceInvariance in Generic Types(Existing in C# )This covariance is not allowedThis code will not compileBefore C# 4.0 Generic Types are Invariant
- 47. Covariance & ContravarianceCovariance in Generic Types of C# 4.0This covariance is allowedpublic interface IEnumerable<out T> : IEnumerable{IEnumerator<T> GetEnumerator();}
- 48. Covariance & ContravarianceContravariance in Generic Types of C# 4.0This Contravariance is allowedpublic interface IComparer<in T>{ public int Compare(T left, T right);}
- 50. Improved COM InterOpOptional “ref” modifier
- 51. Optional and named parameters
- 52. Dynamic objects
- 53. No additional type casts needed
- 54. InterOp type embedding (“No PIA”)Improved COM InterOpPass Parameters without using “ref”
- 55. Improved COM InterOpTake advantage of named parameters & optional arguments
- 56. Improved COM InterOpTake advantage of named parameters & optional arguments
- 58. Journey of C# - RevisitedDynamicFunctional + LINQGenericsStatic Language + Managed Code
- 59. Thank You