Visual Studio 2010and

.NET Framework 4

Training Workshop

What’s New InC# 4.0 and Visual Basic

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Essence versus Ceremony

Simple, Concise, Expressive

Ceremony in C# 3.0Removing “magic values” via temporary

variables

GenerateChart(20, true);

var processCount = 20; var copyToWord = true; GenerateChart(processCount, copyToWord);

Ceremony in C# 3.0Removing “magic values” via temporary

variables

GenerateChart(20, true);

GenerateChart(20 /* processCount */, true /* copyToWord */);

Ceremony in C# 3.0Optional parameters via

method overloading

void GenerateChart(int processCount) { GenerateChart(processCount, false); }

void GenerateChart(int processCount, bool copyToWord) { // Do Something }

Ceremony in C# 3.0Ugly COM Interop and the ever-present

“ref Missing.Value”

var word = new Word.Application(); word.Documents.Add(ref Missing.Value, ref Missing.Value, ref Missing.Value, ref Missing.Value);

Essence vs. Ceremony in C# 4.0

Ceremony in VB 9Backing fields for properties are explicit

Private m_name As String

Public Property Name() As String Get Name = m_name End Get Set (ByVal value As String) m_name = value End End Property

Ceremony in VB 9Popularity of lambda-based libraries cause

problems for VB developers

Sub MyMethod() LambdaCall(Function(i) TempMethod(i) End Function) End Sub

Function TempMethod(Dim param as Integer) As Nothing Console.WriteLine(param)

Return Nothing End Function

Introduction of temporary functions

“Hacks” since statement lambdas not supported

Ceremony in VB 9Line continuations must be specified

by the developer

SomeLongMethodCall(firstParam, _ secondParam, _ thirdParam, _ fourthParam, _ fifthParam)

Essence vs. Ceremony in VB 10

Why a “Dynamic Language Runtime”?

Common Language Runtime

Statically-Typed

C#VB

RubyPython

Dynamically-Typed

Why a “Dynamic Language Runtime”?

Common Language Runtime

Statically-Typed

C#VB

RubyPython

Dynamically-Typed

Dynamic Language Runtime

Ceremony in C# 3.0Dynamic Language interop is

painful

Calculator calc = GetCalculator(); int sum = calc.Add(10, 20);

Ceremony in C# 3.0Dynamic Language interop is

painful

object calc = GetCalculator(); Type calcType = calc.GetType(); object res = calcType.InvokeMember("Add", BindingFlags.InvokeMethod, null, new object[] { 10, 20 }); int sum = Convert.ToInt32(res);

Ceremony in C# 3.0Dynamic Language interop is

painful

ScriptObject calc = GetCalculator(); object res = calc.Invoke("Add", 10, 20); int sum = Convert.ToInt32(res);

Essence in C# 4.0Dynamic Language interopdoesn’t have to be painful!

dynamic calc = GetCalculator(); int sum = calc.Add(10, 20);

Statically typed to be

dynamic

Dynamic method

invocationDynamic

conversion

The power of late-binding

New Features in C# 4.0 & VB 10

Feature VB10 C#4Auto-implemented PropertiesCollection InitializersStatement LambdasImplicit Line Continuation N/ANamed/Optional ParametersLatebinding support (dynamic)Omit ref on COM calls

New in Dev10Already exists in VB9/C#3

New Features in C# 4.0 & VB 10

Feature VB10 C#4Auto-implemented PropertiesCollection InitializersStatement LambdasImplicit Line Continuation N/ANamed/Optional ParametersLatebinding support (dynamic)Omit ref on COM callsInterop with Dynamic LanguagesCo/contravariancePIA deployment not needed

New in Dev10Already exists in VB9/C#3

New Features in C# 4.0 & VB 10

Feature VB10 C#4Auto-implemented PropertiesCollection InitializersStatement LambdasImplicit Line Continuation N/ANamed/Optional ParametersLatebinding support (dynamic)Omit ref on COM callsInterop with Dynamic LanguagesCo/contravariancePIA deployment not neededIteratorsXML Literals

New in Dev10Already exists in VB9/C#3

Fixing The Type System…

Covariance and Contravariance…

sounds complicated…

But it’s not!sort of…

Fixing The Type System…How are generic types “broken” today?

var sheep = new List<Sheep>(); Speak(sheep);

void Speak(IEnumerable<Animal> animals) { // Do something with Animals }

class Animal { } class Sheep : Animal { }

Not Allowed:IEnumerable<Animal> != IEnumerable<Sheep>

Break it down…

Covariance – think “out”

Contravariance – think “in”

Fixing The Type System…Covariance and Contravariance

Sounds complicated!

http://tinyurl.com/genericvariance

Essence versus Ceremony