satisfy your technical curiosity c# 3.0 raj pai group program manager microsoft corporation

Satisfy Your Technical Curiosity

C# 3.0C# 3.0Raj PaiRaj Pai

Group Program ManagerGroup Program ManagerMicrosoft CorporationMicrosoft Corporation

[email protected]@microsoft.com


The Evolution of C#The Evolution of C#

C# 1.0

C# 2.0

C# 3.0

Managed Code

Generics

Language Integrated Query

Satisfy Your Technical CuriositySatisfy Your Technical Curiosity

C# 3.0 Design GoalsC# 3.0 Design Goals

Integrate objects, relational data, and XMLIntegrate objects, relational data, and XML

Increase conciseness of languageIncrease conciseness of language

Add functional programming constructsAdd functional programming constructs

Don’t tie language to specific APIsDon’t tie language to specific APIs

Remain 100% backwards compatibleRemain 100% backwards compatible


Lambda ExpressionsLambda Expressionspublic delegate bool Predicate<T>(T obj);

public class List<T>{ public List<T> FindAll(Predicate<T> test) { List<T> result = new List<T>(); foreach (T item in this) if (test(item)) result.Add(item); return result; } …}


Lambda ExpressionsLambda Expressionspublic class MyClass{ public static void Main() { List<Customer> customers = GetCustomerList(); List<Customer> locals = customers.FindAll( new Predicate<Customer>(StateEqualsWA) ); }

static bool StateEqualsWA(Customer c) { return c.State == "WA"; }}


Lambda ExpressionsLambda Expressionspublic class MyClass{ public static void Main() { List<Customer> customers = GetCustomerList(); List<Customer> locals = customers.FindAll( delegate(Customer c) { return c.State == "WA"; } ); }}


Lambda ExpressionsLambda Expressionspublic class MyClass{ public static void Main() { List<Customer> customers = GetCustomerList(); List<Customer> locals = customers.FindAll(c => c.State == "WA"); }}

Lambda expression


Extension Methods


Extension MethodsExtension Methods

namespace MyStuff{ public static class Extensions { public static string Concatenate(this IEnumerable<string> strings, string separator) {…} }}

using MyStuff;

string[] names = new string[] { "Axel", "Mia", "Niels" };string s = names.Concatenate(", ");

Extensionmethod

Brings extensions into scope

obj.Foo(x, y)XXX.Foo(obj, x, y)

IntelliSense!


Object Initializers


Object InitializersObject Initializerspublic class Point{ private int x, y;

public int X { get { return x; } set { x = value; } } public int Y { get { return y; } set { y = value; } }}

Point a = new Point { X = 0, Y = 1 };

Point a = new Point();a.X = 0;a.Y = 1;

Field or property assignments


Collection InitializersCollection Initializers

List<int> numbers = new List<int> { 1, 10, 100 };

Must implement IEnumerable

List<int> numbers = new List<int>();numbers.Add(1);numbers.Add(10);numbers.Add(100);

Must have public Add method

Dictionary<int, string> spellings = new Dictionary<int, string> { { 0, "Zero" }, { 1, "One" }, { 2, "Two" }, { 3, "Three" } };

Add can take more than one parameter


Anonymous Types


IEnumerable<Contact> phoneListQuery = from c in customers where c.State == "WA" select new Contact { Name = c.Name, Phone = c.Phone };

Anonymous TypesAnonymous Types

public class Contact{ public string Name; public string Phone;}

+


Local Variable Type Inference


Local Variable Type InferenceLocal Variable Type Inferenceint i = 5;string s = "Hello";double d = 1.0;int[] numbers = new int[] {1, 2, 3};Dictionary<int,Order> orders = new Dictionary<int,Order>();

var i = 5;var s = "Hello";var d = 1.0;var numbers = new int[] {1, 2, 3};var orders = new Dictionary<int,Order>();

“The type on the right hand side”


Query Expressions


Query ExpressionsQuery Expressions

from id in source{ from id in source | join id in source on expr equals expr [ into id ] | let id = expr | where condition | orderby ordering, ordering, … } select expr | group expr by key[ into id query ]

Starts with from Zero or more from,

join, let, where, or orderby

Ends with select or group by

Optional into continuation


from c in customerswhere c.State == "WA"select new { c.Name, c.Phone };

customers.Where(c => c.State == "WA").Select(c => new { c.Name, c.Phone });

Query ExpressionsQuery Expressions

Queries translate to method invocationsQueries translate to method invocationsWhere, Join, OrderBy, Select, GroupBy, …Where, Join, OrderBy, Select, GroupBy, …


Expression TreesExpression TreesCode as DataCode as Data

Predicate<Customer> test = c => c.State == "WA";

Predicate<Customer> test = new Predicate<Customer>(XXX);

private static bool XXX(Customer c) { return c.State == "WA";}

public delegate bool Predicate<T>(T item);


Expression TreesExpression TreesCode as DataCode as Data

Expression<Predicate<Customer>> test = c => c.State == "WA";

public delegate bool Predicate<T>(T item);

ParameterExpression c = Expression.Parameter(typeof(Customer), "c");Expression expr = Expression.Equal( Expression.Property(c, typeof(Customer).GetProperty("State")), Expression.Constant("WA") );Expression<Predicate<Customer>> test = Expression.Lambda<Predicate<Customer>>(expr, c);


Automatic Properties


Automatic propertiesAutomatic properties

public class Product{ public string Name; public decimal Price;}



public class Product{ string name; decimal price;

public string Name { get { return name; } set { name = value; } }

public decimal Price { get { return price; } set { price = value; } }}



public class Product{ public string Name { get; set; } public decimal Price { get; set; }}

private string □;

public string Name { get { return □; } set { □ = value; }}

Must have both get and set


Partial Methods


Partial MethodsPartial Methods

partial class Customer{ public string Name { get { … } set { _name = value; } }}


Partial MethodsPartial Methods

partial class Customer{ public string Name { get { … } set { OnNameChanging(value); _name = value; OnNameChanged(); } } partial void OnNameChanging(string value); partial void onNameChanged();}

Partial Method Call

Partial Method Definition


C# 3.0 Language InnovationsC# 3.0 Language Innovationsvar contacts = from c in customers where c.State == "WA" select new { c.Name, c.Phone };

var contacts = customers .Where(c => c.State == "WA") .Select(c => new { c.Name, c.Phone });

Extension methods

Lambda expressions

Query expressions

Object initializers

Anonymous types

Local variable type inference

Expression Trees

Automatic Properties

PartialMethods


C# 3.0 Design GoalsC# 3.0 Design Goals

Integrate objects, relational data, and XMLIntegrate objects, relational data, and XML

Increase conciseness of languageIncrease conciseness of language

Add functional programming constructsAdd functional programming constructs

Don’t tie language to specific APIsDon’t tie language to specific APIs

Remain 100% backwards compatibleRemain 100% backwards compatible


More InformationMore InformationWednesday Thursday

DEV203LINQ Overview14:30 – 15:45

DEV307C# 3.0

9:00 – 10:15

DEV205Visual Studio Orcas

17:45 – 18:45

DEV204ADO.NET vNext10:45 – 12:00

DEV318Visual Basic 9.013:00 – 14:15

http://csharp.net

satisfy your technical curiosity c# 3.0 raj pai group program manager microsoft corporation

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