What’s New in C#6

Jason BockPractice Lead

»http://www.magenic.com

»http://www.jasonbock.net

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»https://www.github.com/jasonbock

» jasonb@magenic.com

Personal Info

https://github.com/JasonBock/

WhatsNewInCSharp6

http://www.slideshare.net/jasonbock/whats-new-in-c6

Downloads

»Language Evolution

»C#6 Features

»Future Directions

Overview

Remember…https://github.com/JasonBock/

WhatsNewInCSharp6

http://www.slideshare.net/jasonbock/whats-new-in-c6

Language Evolution

13 years in the making…

»Classes (and Interfaces) and Structs

»Common Control Flow (switch, if/else, etc.)

»Exception Handling (try/catch/finally)

»Visibility (public/protected/private)

»Delegates and Events

Language Evolution

Version 1

»Generics

» Iterators and Yield

»Static and Partial Classes

»Nullable Types

Language Evolution

Version 2

»LINQ› Object and Collection Initializers

› Anonymous Types

› Expression Trees

› Extension Methods

Language Evolution

Version 3

»Co- and Contravariance

»Dynamic

»Named and Optional Arguments

Language Evolution

Version 4

»Async/Await

Language Evolution

Version 5

Language Evolution

http://static.hdw.eweb4.com/media/wallpapers_1920x1080/fantasy/1/1/dark-tower-fantasy-hd-wallpaper-

1920x1080-5771.jpg

Language Evolution

http://www.dotnetfoundation.org/

The .NET Foundation is an independent organization to foster open development and collaboration around the growing collection of open source technologies for .NET

Language Evolution

https://github.com/dotnet/roslyn

»Auto-property initializers

»Getter-only auto-properties

»Ctor assignment to getter-only autoprops

»Using static members

»Dictionary initializer

»Await in catch/finally

»Exception filters

Language Evolution

Version 6

https://github.com/dotnet/roslyn/wiki/Languages-features-in-C%23-6-and-VB-14

»Expression-bodied members

»Null propagation

»String interpolation

»nameof operator

»#pragma

»Extension Add in collection initializers

» Improved overload resolution

»Auto-property initializers› TODO: Finish

»Getter-only auto-properties› TODO: Finish

»Ctor assignment to getter-only autoprops› TODO: Finish

C#6 Features - Properties

»Using static members› Static members always require the name of the class for resolution

› using “using static” removes that

› E.g. - using static System.Math;

› This also “imports” all the extension methods as well

»Expression-bodied members› If a method is short – e.g. one line of code – you can now define without the curly

braces

› E.g. public int Double(int x) => Add(x, x);

C#6 Features - Functions

»Null conditional› Enables safe access to members in deep object graphs

› E.g. - parent.Child?.ToString()

»String interpolation› Allows you to define the “holes” directly in a formattable string

› E.g. - $"{this.FirstName} {this.LastName}"

»nameof› Provides a way to get the name of a member in code

› Removes the need for magic string usage

› Useful for ArgumentNullException, property changed implementations, WeakEventManager, etc.

C#6 Features – Syntax

»Await in catch/finally› Before C#6, you couldn’t await a method in a catch or finally block. Now you can!

› E.g. – try { /* ... */ } catch(MyException) { await SomeCall(); }

»Exception filters› VB has always had the ability to filter exceptions – that is, only enter a catch block if

some condition is true. Now C#6 has it!

› E.g. – catch(MyException) when (this.HandleIt) { /* ... */ }

C#6 Features - Exceptions

»Dictionary initializer› Is really an “index” initializer. Can be used for dictionaries or any object with an

indexer

› E.g. – var things = new Things { [0] = "Tesla" };

»#pragma› Now works with an identifier as well as an integer, which maps to C# errors

› E.g. these are the same− #pragma warning disable 219

− #pragma warning disable CS0219

› Potentially useful for analyzer errors to disable/enable rather than using SuppressMessageAttribute everywhere

C#6 Features - Miscellaneous

Future Directions

https://dialectline.files.wordpress.com/2012/04/crystal_ball1.jpg

Future Directions

https://github.com/dotnet/roslyn/issues?q=is%3Aopen+is%3Aissue+label%3A%22Up+for+Grabs%22

Future Directions

https://github.com/dotnet/roslyn/issues/98

»My choices/ideas› Generic attributes: [MyMetadata<string>]

› Fault blocks: try { … } fault { … }

› Metaprogramming: [Disposable] public class MyClass

› Reactive programming

Future Directions

What’s New in C#6

Jason BockPractice Lead

Remember… https://github.com/JasonBock/WhatsNewInCSharp6 http://www.slideshare.net/jasonbock/whats-new-in-c6 References in the notes on this slide