The document discusses the new features introduced in C# 6.0. It first provides background on the evolution of C# and the .NET Compiler Platform project called Roslyn. It then outlines the major new features in C# 6.0, including auto-property enhancements, primary constructors, using static, string interpolation, expression-bodied members, declaration expressions, exception filters, binary literals with digit separators, indexed members and element initializers, await in catch/finally blocks, and null-conditional operators. It concludes with information about the presenter and a note about contacting him.

1. C# 6.0 New Features
Mykhaylo Stepanyak
SoftServe, 2015

2. Agenda
 C# Evolution
 .NET Compiler Platform (“Roslyn”)
 C# 6.0 Features
 Demo

3. C# Evolution
C# 1.0
Managed
C# 2.0
Generics
C# 3.0
LINQ
C# 6.0
Compiler Platform
“Roslyn”
C# 5.0
Asynchronous
programming
C# 4.0
Dynamic
programming

4. .NET Compiler Platform (“Roslyn”)
Building compilers and related tools
 Code emitter
 Object model for trees
 .NET Compiler Platform
 Code name “Roslyn”
 Rewrite of the C# and Visual Basic compilers
 Exhaustive set of libraries for
 Code analysis of managed languages
• C#
• Visual Basic
 Language services integrated in Visual Studio
• Refactoring
• IntelliSense and code browsing

5. Why Microsoft Built “Roslyn”
Faster turn-around to build new language features
 Support experimentation and prototyping
• E.g. C# 6.0 has a bunch of small features
 Comprehensive set of rich APIs
• Syntax trees and visitors
• Semantic analysis
• Compilation model
 Lights up in all compiler contexts at once
• Richer tooling can be built
Openness and ecosystem
 Allow 3rdparties to build extensions
• Democratize refactorings and other tools
• Eliminate private APIs for Visual Studio
 Education about compiler internals
 Open source

6. What’s inside?

7. Compilation Steps

8. Compilation Steps

9. Compilation Steps

10. Compilation Steps

11. Compliers APIs

12. Language Services

13. C# 6.0 Features

14. Auto-property enhancements
public class Customer
{
public string First { get; set; } = "Jane";
public string Last { get; set; } = "Doe";
}
public class Customer
{
public string First { get; } = "Jane";
public string Last { get; } = "Doe";
}

15. Primary constructors
public class Customer(string first, string last)
{
public string First { get; } = first;
public string Last { get; } = last;
}

16. Using static
using System.Console;
using System.Math;
class Program
{
static void Main()
{
WriteLine(Sqrt(3*3 + 4*4));
}
}

17. String interpolation
var s = "{p.Name} is {p.Age} year{s} old";
var s = "{p.Name} is {p.Age} year{(p.Age == 1 ? "" : "s")} old";

18. Expression-bodied function members
public Point Move(int dx, int dy) => new Point(x + dx, y + dy);
public static Complex operator +(Complex a, Complex b) => a.Add(b);
public static implicit operator string(Person p) => "{p.First} {p.Last}";

19. Declaration expressions
if (int.TryParse(s, out int i)) { … }
GetCoordinates(out var x, out var y);
Console.WriteLine("Result: {0}", (int x = GetValue()) * x);
if ((string s = o as string) != null) { … s … }

20. Exception filters
try { … }
catch (MyException e) if (myfilter(e))
{
…
}

21. Binary literals and digit separators (Try them
out in VB)
var bits = 0b00101110;
var bits = 0b0010_1110;
var hex = 0x00_2E;
var dec = 1_234_567_890;

22. Indexed members and element initializers
var numbers = new Dictionary<int, string> {
[7] = "seven",
[9] = "nine",
[13] = "thirteen"
};
var customer = new JsonData {
$first = "Anders", // => ["first"] = "Anders"
$last = "Hejlsberg" // => ["last"] = "Hejlsberg"
}
string first = customer.$first; // => customer["first"]

23. Await in catch and finally blocks
Resource res = null;
try
{
res = await Resource.OpenAsync(…); // You could do this.
…
}
catch(ResourceException e)
{
await Resource.LogAsync(res, e); // Now you can do this …
}
finally
{
if (res != null) await res.CloseAsync(); // … and this.
}

24. Null-conditional operators
int? length = customers?.Length; // null if customers is null
Customer first = customers?[0]; // null if customers is null
int? first = customers?[0].Orders.Count(); // if customers is null, the result is null

25. Demo

26. Mykhaylo Stepanyak
mstepanyak@gmail.com
Lviv, Ukraine
Contacts