C# 6.0 - What?! C# is being updated?

C# 6.0What?! C# is Being Updated?

Filip Ekberg

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Filip EkbergC# MVP

http://fekberg.com

@fekberg

C# Smorgasbord

/ Copyright ©2014 by Readify Pty Ltd3

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History of C#


http://en.wikipedia.org/wiki/C_Sharp_(programming_language)#History

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C# 2.0› Generics

› Partial types

› Anonymous methods

› Iterators

› Nullable types

› Getter/Setter separate accessibility

› Static classes

› And more..

/ Copyright ©2014 by Readify Pty Ltd5 @fekberg

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C# 3.0› Implicitly typed local variables

› Object and collection initializers

› Auto-properties

› Anonymous types

› Extension methods

› Query expressions

› Lambda expressions

› Expression trees

› And more..


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C# 4.0› Dynamic binding

› Named and optional parameters

› Generic co-and contravariance

› And more..


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C# 5.0› Asynchronous methods

› Caller info attributes


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The state of the Compiler› It’s been a black box

› Roslyn to the rescue!

› .NET Compiler Platform

› Microsoft decides to re-write the compiler

› Compiler written in C#

› Easier to extend and maintain

› Open Source!


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C# 6.0 Overview› Auto-property initializers

› Getter-only auto-properties

› Assignment to getter-only auto-properties

from constructor

› Parameter-less structconstructors

› Using Statements for Static Members

› Dictionary Initializer

› Await in catch/finally

› Exception filters

› Expression-bodied members


› Null propagation

› String interpolation

› nameofoperator

› And more..

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Auto-Property Initializers


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Auto-property initializers in a nutshell


class Person{

public string Name { get; set; }}

class Person{

public string Name { get; } = "Anonymous";}

= "Anonymous";

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class Person{

public string Name { get; }

public Person(){

Name = "Filip";}

}

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class Person{

private readonly string <Name>k__BackingField = "Filip";

public string Name{

get{

return this.<Name>k__BackingField;}

}}

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Parameter-lessstructconstructors


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Parameter-less structconstructors in a nutshell


struct Point{

public int X { get; }public int Y { get; }

}

Read Only!

public Point(){

X = 100;Y = 100;

}

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Read Only!

struct Point{

private readonly int <X>k__BackingField;private readonly int <Y>k__BackingField;

public int X{

get{

return this.<X>k__BackingField;}

}public int Y{

get{

return this.<Y>k__BackingField;}

}public Point(){

this.<X>k__BackingField = 100;this.<Y>k__BackingField = 100;

}}

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Read Only!

struct Point{

public int X { get; }public int Y { get; }

public Point(int x, int y){

X = x;Y = y;

}

public Point() : this(100, 100){}

}

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Using Statements for Static Members


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Using Statements for Static Members in a nutshell


class Program{

static void Main(string[] args){

var angle = 90d;Console.WriteLine(Math.Sin(angle));

}}

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using System.Console;using System.Math;

class Program{


var angle = 90d;WriteLine(Sin(angle));

}}

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using System.Console;using System.Linq.Enumerable;

class Program{


foreach (var i in Range(0, 10)){

WriteLine(i);}

}}

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Dictionary Initializers


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Dictionary Initializers in a nutshell


var people = new Dictionary<string, Person>{

["Filip"] = new Person()};

var answers = new Dictionary<int, string>{

[42] = "the answer to life the universe and everything"};

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Await inside Finally block


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Await + Finally in a nutshell


public async Task DownloadAsync(){

}

try{ }catch{

await Task.Delay(2000);}finally{

await Task.Delay(2000);}

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Exception Filters


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Exception filters in a nutshell


try{

throw new CustomException { Severity = 100 };}catch (CustomException ex) if (ex.Severity > 50){

Console.WriteLine("*BING BING* WARNING *BING BING*");}catch (CustomException ex){

Console.WriteLine("Whooops!");}

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Null Propagation


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Null propagation in a nutshell


class Person{

public string Name { get; set; }public Address Address { get; set; }

}

Console.WriteLine(filip.Address.AddressLine1);

var filip = new Person{

Name = "Filip"};

class Address{

public string AddressLine1 { get; set; }public string AddressLine2 { get; set; }

}

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class Person{


}

Console.WriteLine(filip.Address.AddressLine1);


Name = "Filip"};

class Address{


}

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class Person{


}

Console.WriteLine(filip.Address.AddressLine1);Console.WriteLine(filip.Address == null ? "No Address" : filip.Address.AddressLine1);


Name = "Filip"};

class Address{


}

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class Person{


}

Console.WriteLine(filip.Address.AddressLine1);Console.WriteLine(filip.Address == null ? "No Address" : filip.Address.AddressLine1);

Console.WriteLine(filip?.Address?.AddressLine1 ?? "No Address");


Name = "Filip"};

class Address{


}

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var people = new[]{

new Person(),null

};

WriteLine(people[0]?.Name);

WriteLine(people[1]?.Name);

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Person[] people = null;

WriteLine(people?[0]?.Name);

Person[] people = null;Console.WriteLine(

(people != null) ? ((people[0] == null) ? null : people[0].Name) : null

);

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Expression-bodied members


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Expression-bodied members in a nutshell


class Rectangle{

public double Width { get; set; }public double Height { get; set; }

public double Area => Width * Height;}

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Expression-bodied members in a nutshell


class Rectangle{

public double Width { get; set; }public double Height { get; set; }

public override string ToString() => "My Width is \{Width} and my Height is \{Height}";

}

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String interpolation


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String interpolation in a nutshell



public override string ToString() => $"My Width is {Width} and my Height is {Height}";

Syntax will change in a later release to the following:

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public override string ToString(){

object[] args = new object[] { this.Width, this.Height };return string.Format("My Width is {0} and my Height is {1}", args);

}

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int age = 28;var result = "Hello there, I'm \{age : D5} years old!";WriteLine(result);

int num = 28;object[] objArray1 = new object[] { num };Console.WriteLine(string.Format("Hello there, I'm {0:D5} years old!", objArray1));

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nameofoperator


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nameof operator in a nutshell



WriteLine("Parameter name is: \{nameof(args)}");}

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nameof operator in a nutshell


public double CalculateArea(int width, int height){

if (width <= 0){

throw new ArgumentException("Parameter \{nameof(width)} cannot be less than 0");}

return width * height;}

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DemoC# 6.0 Language Features in Visual Studio 2015


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There’s more??


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What about C# 7.0?› Binary literals and Digit separators


0b00001000

0xFF_00_FA_AF

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› Event initializers


var client = new WebClient{

DownloadFileCompleted += DownloadFileCompletedHandler

};

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› Field targets on auto-properties


[field: NonSerialized]public int Age { get; set; }

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› Semicolon operator


var y = (var x = Foo(); Write(x); x * x);

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› Using params with IEnumerable


int Avg(params IEnumerable<int> numbers)

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› Declaration Expressions


public void CalculateAgeBasedOn(int birthYear, out int age){

age = DateTime.Now.Year - birthYear;}

CalculateAgeBasedOn(1987, out var age);

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› Declaration Expressions

› Primary Constructors

› And possibly more...


class Person(string name, int age){

private string _name = name;private int _age = age;

}

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More with Roslyn


› Exposes the Compiler APIs

› Plugins powered by Roslyn

› Analyze code

› Re-write code

@fekberg

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Summary


› C# 6.0 is awesome

› There’s a lot of change in C# 6.0

› .NET Compiler Platform ("Roslyn") makes it easy for Microsoft to

improve the language

› There’s a lot of interesting features that could go in C# 7.0

@fekberg

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Questions?


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Thank you!

http://fekberg.com

@fekberg

C# Smorgasbord


C# 6.0 - What?! C# is being updated?

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