Presentación del Futuro del lenguaje C#

2. C# 1.0 C# 2.0 Código manejado Generics

5. class Program { static IEnumerable<int> Range(int start, int count) { for (int i = 0; i < count; i++) yield return start + i; } static IEnumerable<int> Squares(IEnumerable<int> source) { foreach (int x in source) yield return x * x; } static void Main() { foreach (int i in Squares(Range(0, 10))) Console.WriteLine(i); } } 0 1 4 9 16 25 36 49 64 81

6. C# 1.0 C# 2.0 C# 3.0 Código manejado Generics Language Integrated Query (Linq)

8. var contacts = from c in customers where c.State == &quot;WA&quot; select new { c.Name, c.Phone }; var contacts = customers .Where(c => c.State == &quot;WA&quot;) .Select(c => new { c.Name, c.Phone }); Métodos de Extención Expreciones Lambda Query expressions Inicializadores de Objetos Tipos Anónimos Inferencia de tipos en variables locales Expression Trees Propiedades Automáticas Métodos Parciales

11. Qué Cómo Imperativo Declarativo

15. C# 1.0 C# 2.0 C# 3.0 Código manejado Generics Language Integrated Query C# 4.0 Programación dinámica

17. Python Binder Ruby Binder COM Binder JavaScript Binder Object Binder Dynamic Language Runtime Expression Trees Dynamic Dispatch Call Site Caching IronPython IronRuby C# VB.NET Otros…

18. Calculator calc = GetCalculator(); int sum = calc.Add(10, 20); object calc = GetCalculator(); Type calcType = calc.GetType(); object res = calcType.InvokeMember( &quot;Add&quot; , BindingFlags.InvokeMethod, null , new object [] { 10, 20 }); int sum = Convert.ToInt32(res); ScriptObject calc = GetCalculator(); object res = calc.Invoke( &quot;Add&quot; , 10, 20); int sum = Convert .ToInt32(res); dynamic calc = GetCalculator(); int sum = calc.Add(10, 20); Estáticamente tipado para ser dinámico Invocación dinámica de métodos Conversión dinámica

20. public static class Math { public static decimal Abs( decimal value); public static double Abs( double value); public static float Abs( float value); public static int Abs( int value); public static long Abs( long value); public static sbyte Abs( sbyte value); public static short Abs( short value); ... } double x = 1.75; double y = Math .Abs(x); dynamic x = 1.75; dynamic y = Math .Abs(x); Método elegido en tiempo de compilación: double Abs(double x) Método elegido en tiempo de ejecución : double Abs(double x) dynamic x = 2; dynamic y = Math .Abs(x); Método elegido en tiempo de ejecución : int Abs(int x)

22. public StreamReader OpenTextFile( string path, Encoding encoding, bool detectEncoding, int bufferSize); public StreamReader OpenTextFile( string path, Encoding encoding, bool detectEncoding); public StreamReader OpenTextFile( string path, Encoding encoding); public StreamReader OpenTextFile( string path); Método primario Sobrecarga secundaria Llama al primario con valores por defecto

23. public StreamReader OpenTextFile( string path, Encoding encoding, bool detectEncoding, int bufferSize); public StreamReader OpenTextFile( string path, Encoding encoding = null , bool detectEncoding = true , int bufferSize = 1024); Parámetros opcionales OpenTextFile( &quot;foo.txt&quot; , Encoding .UTF8); OpenTextFile( &quot;foo.txt&quot; , Encoding .UTF8, bufferSize: 4096); Argumentos por nombre OpenTextFile( bufferSize: 4096, path: &quot;foo.txt&quot; , detectEncoding: false ); Argumentos por nombre al final Los no opcionales deben ser especificados Los Argumentos son evaluados en el orden que se escriben Argumentos por nombre pueden aparecer desorden

24. object fileName = &quot;Test.docx&quot; ; object missing = System.Reflection. Missing .Value; doc.SaveAs( ref fileName, 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( &quot;Test.docx&quot; );

26. public abstract class DynamicObject : IDynamicObject { public virtual object GetMember( GetMemberBinder info); public virtual object SetMember( SetMemberBinder info, object value); public virtual object DeleteMember( DeleteMemberBinder info); public virtual object UnaryOperation( UnaryOperationBinder info); public virtual object BinaryOperation( BinaryOperationBinder info, object arg); public virtual object Convert( ConvertBinder info); public virtual object Invoke( InvokeBinder info, object [] args); public virtual object InvokeMember( InvokeMemberBinder info, object [] args); public virtual object CreateInstance( CreateInstanceBinder info, object [] args); public virtual object GetIndex( GetIndexBinder info, object [] indices); public virtual object SetIndex( SetIndexBinder info, object [] indices, object value); public virtual object DeleteIndex (DeleteIndexBinder info, object [] indices); public MetaObject IDynamicObject .GetMetaObject(); }

29. void Process( object [] objects) { … } string [] strings = GetStringArray(); Process(strings); void Process( object [] objects) { objects[0] = &quot;Hello&quot; ; // Ok objects[1] = new Button (); // Exception! } List < string > strings = GetStringList(); Process(strings); void Process( IEnumerable < object > objects) { … } .NET arrays are co-variant … but not safely co-variant Until now, C# generics have been invariant void Process( IEnumerable < object > objects) { // IEnumerable<T> is read-only and // therefore safely co-variant } C# 4.0 supports safe co- and contra-variance

30. public interface IEnumerable <T> { IEnumerator <T> GetEnumerator(); } public interface IEnumerator <T> { T Current { get ; } bool MoveNext(); } public interface IEnumerable < out T> { IEnumerator <T> GetEnumerator(); } public interface IEnumerator < out T> { T Current { get ; } bool MoveNext(); } out = Co-variant Output positions only IEnumerable < string > strings = GetStrings(); IEnumerable < object > objects = strings; Can be treated as less derived public interface IComparer <T> { int Compare(T x, T y); } public interface IComparer < in T> { int Compare(T x, T y); } IComparer < object > objComp = GetComparer(); IComparer < string > strComp = objComp; in = Contra-variant Input positions only Can be treated as more derived

33. C# 1.0 C# 2.0 C# 3.0 Managed Code Generics Language Integrated Query C# 4.0 Dynamic Programming

34. Source code Source code Source File Source code Source code .NET Assembly Meta-programming Read-Eval-Print Loop Language Object Model DSL Embedding Compiler Compiler Class Field public Foo private string X

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