C# in the Big World

1. Required Slide SESSION CODE: DEV404 C# in the Big World Mads Torgersen Program Manager Microsoft Corporation

2. C# in the Big World • New features • Dynamic • Named and optional arguments • COM interop features • The design of dynamic

3. The DLR on the CLR • Common Language Runtime – CLR: • Common platform for static languages • Facilitates great interop

4. The DLR on the CLR • Common Language Runtime – CLR: • Common platform for static languages • Facilitates great interop • Dynamic Language Runtime – DLR: • Common platform for dynamic languages • Facilitates great interop

5. The DLR on the CLR • Common Language Runtime – CLR: • Common platform for static languages • Facilitates great interop • Dynamic Language Runtime – DLR: • Common platform for dynamic languages • Facilitates great interop

6. Dynamic Objects • Implement their own binding • Programmatically describes meaning of operations • The DLR caches and optimizes • Built by dynamic languages – or by you!

7. Why Dynamic in C#? • Build on DLR opportunity • Use code from dynamic languages • Use other dynamic object models • Improve COM interop

8. Dynamic Language Runtime (DLR) IronPython IronRuby C# VB.NET Others… Dynamic Language Runtime Expression Trees Dynamic Dispatch Call Site Caching ObjectBinder JavaScriptBinder PythonBinder RubyBinder COMBinder

9. The dynamic Type in C# Calculator calc = GetCalculator(); int sum = calc.Add(10, 20); object calc = GetCalculator(); TypecalcType = calc.GetType(); object res = calcType.InvokeMember("Add", BindingFlags.InvokeMethod, null, newobject[] { 10, 20 }); int sum = Convert.ToInt32(res); ScriptObject calc = GetCalculator(); object res = calc.Invoke("Add", 10, 20); int sum = Convert.ToInt32(res); Statically typed to be dynamic dynamic calc = GetCalculator(); int sum = calc.Add(10, 20); Dynamic conversion Dynamic method invocation

10. Dynamic DEMO

11. System.Dynamic.DynamicObject publicclassDynamicObject : IDynamicMetaObjectProvider { publicvirtualIEnumerable<string> GetDynamicMemberNames(); publicvirtualDynamicMetaObjectGetMetaObject(Expression parameter); publicvirtualboolTryBinaryOperation(BinaryOperationBinder binder, objectarg, outobject result); publicvirtualboolTryConvert(ConvertBinder binder, outobject result); publicvirtualboolTryCreateInstance(CreateInstanceBinder binder, object[] args, outobject result); publicvirtualboolTryDeleteIndex(DeleteIndexBinder binder, object[] indexes); publicvirtualboolTryDeleteMember(DeleteMemberBinder binder); publicvirtualboolTryGetIndex(GetIndexBinder binder, object[] indexes, outobject result); publicvirtualboolTryGetMember(GetMemberBinder binder, outobject result); publicvirtualboolTryInvoke(InvokeBinder binder, object[] args, outobject result); publicvirtualboolTryInvokeMember(InvokeMemberBinder binder, object[] args, outobject result); publicvirtualboolTrySetIndex(SetIndexBinder binder, object[] indexes, object value); publicvirtualboolTrySetMember(SetMemberBinder binder, object value); publicvirtualboolTryUnaryOperation(UnaryOperationBinder binder, outobject result); }

12. DynamicObject DEMO

13. Optional and Named Parameters publicStreamReaderOpenTextFile( string path, Encodingencoding, booldetectEncoding, intbufferSize); Primary method Secondary overloads publicStreamReaderOpenTextFile( string path, Encodingencoding, booldetectEncoding); publicStreamReaderOpenTextFile( string path, Encodingencoding); publicStreamReaderOpenTextFile( string path); Call primary with default values

14. Optional and Named Parameters Optional parameters publicStreamReaderOpenTextFile( string path, Encodingencoding, booldetectEncoding, intbufferSize); publicStreamReaderOpenTextFile( string path, Encodingencoding = null, booldetectEncoding = true, intbufferSize = 1024); Named argument OpenTextFile("foo.txt", Encoding.UTF8); OpenTextFile("foo.txt", Encoding.UTF8, bufferSize: 4096); Named arguments can be in any order Evaluated inorder written Named arguments must be last OpenTextFile( bufferSize: 4096, path: "foo.txt", detectEncoding: false); Non-optional must be specified

15. Improved COM Interoperability objectfileName = "Test.docx"; object missing = System.Reflection.Missing.Value; doc.SaveAs(reffileName, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing); doc.SaveAs("Test.docx");

16. Improved COM Interoperability • Optional and named parameters • Indexed properties • Optional “ref” modifier • Interop type embedding (“No PIA”) • Automatic object  dynamic mapping

17. Improved COM Interoperability DEMO

18. Designing DynamicInitial sentiment • C# is not a dynamic language! • Dynamic is a dangerous foreign element • It should be syntactically explicit

19. Static Example string[]strings = GetStrings(); string last = strings[strings.Length – 1];

20. Explicit Dynamic Operations object strings = GetDynamicObject(); string last = strings[strings.Length – 1]; object strings = GetDynamicObject(); string last = strings[strings~.Length – 1]; object strings = GetDynamicObject(); string last = strings~[strings~.Length – 1]; object strings = GetDynamicObject(); string last = strings~[strings~.Length~– 1]; object strings = GetDynamicObject(); string last = (string)strings~[strings~.Length~– 1]; object strings = GetDynamicObject(); string last = ~(string)strings~[strings~.Length~– 1];

21. Explicit Dynamic Operations • Reads horribly! • Insight: Dynamic operations travel in packs! object strings = GetDynamicObject(); string last = ~(string)strings~[strings~.Length~– 1]; 

22. Dynamic Blocks object strings = GetDynamicObject();string last; dynamic {last = strings[strings.Length– 1]; }

23. Dynamic Blocks • Different “dialect” of C# inside • Opt out with static contexts? • Lose sight of big contexts • Insight: Dynamicness flows from within object strings = GetDynamicObject();string last; dynamic {last = strings[strings.Length– 1]; } 

24. Contagious Dynamic Expressions object strings = GetDynamicObject(); string last = strings[dynamic(strings).Length – 1];

25. Contagious Dynamic Expressions • Rules of propagation – which operations are dynamic? • Factoring out subexpressions is hard – what is their type? • Insight: Dynamicness follows the objects object strings = GetDynamicObject(); string last = strings[dynamic(strings).Length – 1]; 

26. The dynamic Type dynamic strings = GetDynamicObject(); string last = strings[strings.Length– 1];

27. The dynamic Type • Propagates through the types • Reads like normal C#! dynamic strings = GetDynamicObject(); string last = strings[strings.Length– 1]; 

28. Why is this OK?What Happened to Syntactically Explicit? • Embrace dynamicness • You can’t make a language feature that is “built to be ugly” • Dynamic isn’t there to take away safety • But to make ugly code nice • Dynamicness is still explicit – just not in syntax • What better way to express lack of typing than through types?

29. Type or Type Modifier? • Generality: • Static binding of Foo’s members • Dynamic binding of the rest • Simplicity: • Dynamic binding of all members • Even those on Object dynamic Foo foo = GetDynamicFoo();  dynamic foo = GetDynamicFoo(); 

30. Dynamic Binding When? • When the receiver is dynamic: • Forces you to choose a type • When anysubexpression is dynamic: • Softer “landing” back in type land dynamic result = Math.Abs((double)d);  dynamic result = Math.Abs(d); 

31. Dynamic Operations • Dynamic result: • Method call Math.Abs(d) • Invocationd(“Hello”) • Member access d.Length • Operator application 4+ d • Indexing d[“Hello”] • Static result: • Conversions (double)d • Object creation newFoo(d)

32. How Dynamic? • “Just enough” dynamicness • Nobody uses your runtime type unless you let them • Principle of least surprise: • Argument’s contribution to binding is invariant M(d, GetFoo()); Bind with compile-time type Bind with runtime type

33. Summary: The Meaning of dynamic dynamicmeans “use my runtime type for binding”

34. Summary: The Reason for dynamicWhich would you rather see – or write? TypecalcType = calc.GetType(); object res = calcType.InvokeMember("Add", BindingFlags.InvokeMethod, null, newobject[] { 10, 20 }); int sum = Convert.ToInt32(res); int sum = calc.Add(10, 20);

35. Takeaways • C# 4.0 is about interacting with a bigger world • Dynamic allows anything to “look like an object” • Named and optional eliminate overloads and boilerplate • COM interop is finally natural in C#

36. Required Slide Speakers, please list the Breakout Sessions, Interactive Sessions, Labs and Demo Stations that are related to your session. Related Content – Breakout Sessions DEV307: F# in Microsoft Visual Studio 2010 (6/10 from 9:45am – 11:00am) DEV315: Microsoft Visual Studio 2010 Tips and Tricks (6/8 from 5:00pm – 6:15pm) DEV316: Modern Programming with C++Ox in Microsoft Visual C++ 2010 (6/8 from 3:15pm – 4:30pm) DEV319: Scale and Productivity for C++ Developers with Microsoft Visual Studio 2010 (6/9 from 8:00am – 9:15am) DEV401: Advanced Use of the new Microsoft Visual Basic 2010 Language Features (6/9 from 9:45am – 11:00am) DEV404: C# in the Big World (6/8 from 1:30pm – 2:45pm) DEV406: Integrating Dynamic Languages into Your Enterprise Applications (6/8 from 8am – 9:15am) DEV407: Maintaining and Modernizing Existing Applications with Microsoft Visual Studio 2010 (6/10 from 8:00am – 9:15am)

37. Required Slide Speakers, please list the Breakout Sessions, Interactive Sessions, Labs and Demo Stations that are related to your session. Related Content – Interactive Sessions and HOL's DEV03-INT: Meet the C# team (6/9 from 1:30-2:45pm) DEV04-INT: Meet the VB team (6/10 from 3:15 – 4:30pm) DEV09-INT: Microsoft Visual Basic and C# IDE Tips and Tricks (6/7 from 4:30pm -5:45pm) DEV10-INT: Using Dynamic Languages to build Scriptable Applications ((6/9 from 8:00am -9:15am) DEV11 –INT: IronPython Tools (6/10 from 5:00pm – 6:15pm) DEV05-HOL: Introduction to F#

38. Required Slide Track PMs will supply the content for this slide, which will be inserted during the final scrub. Track Resources • Visual Studio – http://www.microsoft.com/visualstudio/en-us/ • Soma’s Blog – http://blogs.msdn.com/b/somasegar/ • MSDN Data Developer Center – http://msdn.com/data • ADO.NET Team Blog – http://blogs.msdn.com/adonet • WCF Data Services Team Blog – http://blogs.msdn.com/astoriateam • EF Design Blog – http://blogs.msdn.com/efdesign

39. Required Slide Resources Learning • Sessions On-Demand & Community • Microsoft Certification & Training Resources www.microsoft.com/teched www.microsoft.com/learning • Resources for IT Professionals • Resources for Developers • http://microsoft.com/technet • http://microsoft.com/msdn

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