C# 6.0 Introduction

6.0
Olav Haugen
Åpen fagkveld - Webstep - 9.10.2014

C-like Object Oriented Language
1999
Anders Hejlsberg
etablerer et team
som skal lage Cool

.NET blir annonsert.
"Cool" har endret navn til C♯
2000
“Mye nærmere C++ i design”
PDC
“Klone av java”
“Mangel på innovasjon”
Andy!

C# 1.0 blir lansert sammen med
.NET 1.0 og Visual Studio .NET 2002
2002

.NET 2.0 og Visual Studio 2005
2005
Generics
Partial types
Anonymous methods
Iterators
Nullable types
Getter/setter separate accessibility
Method group conversions (delegates)
Co- and Contra-variance for delegates
Static classes

.NET 3.5, LINQ og Visual Studio 2008
2007
Implicitly typed local variables
Object and collection initializers
Auto-Implemented properties
Anonymous types
Extension methods
Query expressions
Lambda expressions
Expression trees
Partial methods

2010
Dynamic binding
Named and optional arguments
Generic co- and contravariance
Embedded interop types ("NoPIA")

C# 5.0 blir lansert samme med
2012
Asynchronous methods
Caller info attributes

2014
C# 6.0 blir lansert
uten noen features?

C# 6.0
Auto-property enhancements
Primary constructors
Expression bodied function members
Initializers in structs
Using static
Exception filters
Declaration expressions
Nameof expressions
Null-conditional operators
Index initializers
Await in catch and finally blocks
Binary literals and digit separators
Extension Add methods in collection initializers
Improved overload resolution

Roslyn
.NET compiler blir open source
https://roslyn.codeplex.com/

2014
3. juni Visual Studio 2014 CTP
8. juli Visual Studio 2014 CTP 2
18. aug Visual Studio 2014 CTP 3
6. okt Visual Studio 2014 CTP 4
C# 6.0 og .NET tilgjengelig for community før lansering.
Man kan til og med bidra på utvikligen av C#!

public class User
{
public User()
{
Name = "Olav";
}
public string Name { get; set; }
}
Før: Initialisere public properties

public class User
{
public string Name { get; set; } = "Olav";
}
C# 6.0: Initialisere public properties

public class User
{
private readonly string _name;
public User()
{
_name = "Olav";
}
public string Name
{
get
{
return _name;
}
}
}
Før: Initialisere readonly properties

public class User
{
public string Name { get; } = "Olav";
}
C# 6.0: Initialisere readonly properties

public class User
{
private string firstName;
private string lastName;
public User(string firstName, string lastName)
{
this.firstName = firstName;
this.lastName = lastName;
}
}
Før:

public class User(string firstName, string lastName)
{
private string firstName = firstName;
private string lastName = lastName;
}
C# 6.0:

public class User(string name)
{
{
if (name == null)
{
throw new
ArgumentNullException("name");
}
}
private string name = name;
}
C# 6.0: Constructor bodies

public class User
{
private readonly string _firstName;
private readonly string _lastName;
public User(string firstName, string lastName)
{
_firstName = firstName;
_lastName = lastName;
}
public string FirstName
{
get
{
return _firstName;
}
}
public string LastName
{
get
{
return _lastName;
}
}
}
Før: Sette readonly properties

public class User(string firstName, string
lastName)
{
public string FirstName { get; } = firstName;
public string LastName { get; } = lastName;
}
C# 6.0: Sette readonly properties

Expression bodied
function members

public int Add(int x, int y)
{
return x + y;
}
Før: Enkel metode
public int Add(int x, int y) => x + y;
C# 6.0: Enkel metode

public string Name
{
get
{
return FirstName + " " + LastName;
}
}
Før: Property getter
public string Name => FirstName + " " + LastName;
C# 6.0: Property getter

public string GetFirstUserName(IEnumerable<Customer> customers)
{
if (customers != null)
{
var customer = customers.FirstOrDefault();
if (customer != null)
{
if (customer.Users != null)
{
var user = customer.Users.FirstOrDefault();
if (user != null)
{
return user.Name;
}
}
}
}
return null;
}
Før:

public string GetFirstUserName(IEnumerable<Customer> customers)
{
return customers?.FirstOrDefault()?.Users?.FirstOrDefault()?.Name;
}
C# 6.0:

C# 6.0:
// Null hvis users er null
int? numberOfUsers = users?.Length;
// Null hvis users er null
User first = users?[0];
// Chaining
int? numberOfOrders = users?[0].Orders?.Count();
// Et nytt pattern?
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(X)));

using System;
class Program
{
static void Main()
{
Console.WriteLine("Hello world!");
}
}
Før:
Using static

using System.Console;
class Program
{
static void Main()
{
WriteLine("Hello world!");
}
}
C# 6.0:
Using static

public int ParseIntOrDefault(string numberCandidate)
{
int number;
int.TryParse(numberCandidate, out number);
return number;
}
Før:

public int ParseIntOrDefault(string numberCandidate)
{
int.TryParse(numberCandidate, out int number);
return number;
}
C# 6.0:

nameof expressions
public class Person(string name)
{
{
if (name == null)
throw new ArgumentNullException(nameof(name));
}
}
Skriver ut navnet på variabler og metoder.
Gjør det lettere når man skal refaktorere kode.
WriteLine(nameof(Console.WriteLine)); // Skriver "WriteLine"
WriteLine(nameof(Person.Name)); // Skriver "Name"

Binary literals &
digit separators

Binary literals and digit separators
var bits = 0b0010_1110;
var hex = 0x00_2E;
var dec = 1_234_567_890;
Øker lesbarheten på bits, hex og tall

Exception filters
try { ... }
catch (MyException e) if (SomeCondition(e))
{
}
Fang en exception basert på en betingelse
Bedre enn å kaste exception videre, siden stacktracen
blir uberørt.

Exception filters
Kan også (mis?)brukes til logging
try { ... }
catch (MyException e) if (Log(e)) {}
public bool Log(Exception e)
{
// Logg exception
// Returner false for at exception ikke catches
return false;
}

.NET Fiddle
C# 6.0 rett i nettleseren

Visual Studio 2014 CTP
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
…
<LangVersion>experimental</LangVersion>
</PropertyGroup>
Rediger .csproj-fil for å aktivere C# 6.0:
Last ned:
http://www.visualstudio.com/en-us/downloads/visual-studio-14-ctp-vs.aspx
Også tilgjengelig ferdiginstallert i Azure sitt Virtual Machine Gallery

Følg utvikling av C# 6.0
https://roslyn.codeplex.com/
• Følg status på C# features
• Referat fra designmøter
• Fiks bugs
• Foreslå nye features (vil nok mest sannsynlig bli avvist)

C# 6.0 Introduction

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