C# 6 in 30 Minutes

Writer and consultant

• Microsoft C# MVP and CodeProject MVP
• Active contributions to open-source projects
• Company workshops, talks and IT consulting

Languages and technologies

• C#, JavaScript and C/C++
• Full web stack (client and server)
• High Performance and Embedded Computing

1. Strings
2. Exceptions
3. Properties / Methods
4. Initialization
5. Elvis

• Introducing string interpolation yields
  • Ordinary strings ""
  • Literal strings @""
  • Interpolated strings $""
• Parts of the interpolation requires a new class
• But we can easily provide our own implementation, e.g.,
• System.FormattableString in conjunction with
• System.Runtime.CompilerServices.FormattableStringFactory
• FormattableString Create(string, params object[])

var number = 31;
 
var a = $"We can also compute stuff {5 * 8 + number}!";
 
var b = $"Using formatters is possible, like {number:X2}!";
 
var c = System.FormattableString.Invariant(
               $"Printing invariant PI: {Math.PI}.");

• Exception filtering with when
• Now we can await in catch-blocks

public static async Task<String> ReadFileAsync(this String fn) {
	try
	{
		using (var fs = File.OpenRead(fn))
		{
			using (var sr = new StreamReader(fs))
				return await sr.ReadToEndAsync();
		}
	}
	catch (PathTooLongException ex) when (fn.Length < 255)
	{
		await WriteExceptionToLogAsync(ex);
		return null;
	}
}

• True readonly properties are now possible
• Method expressions for convenience
• Combine both for computed properties

public String FileName { get; };
 
public Int32 AnswerToEverything => 42;
 
public static Double Arcosh(Double x) =>
                     Math.Log(x + Math.Sqrt(x * x - 1.0));

• Make methods of atatic class available with using static
• New index initializers for consistent object initialization
• This new method works with any defined indexer

using static System.Math;
using static System.FormattableString;
 
public class Test {
	public String FileName { get; } = "my-file.txt";
 
	static Double Arcosh(Double x) => Log(x + Sqrt(x * x - 1.0));
 
	public static Dictionary<Double, String> CreateTable() {
		return new Dictionary<Double, String> {
			[1.0] = Invariant($"1.0 => {Arcosh(1.0)}"),
			[1.5] = Invariant($"1.5 => {Arcosh(1.5)}")
		};
	}
}

• Resolve names using the nameof operator
• probably the most important feature of C# 6: ?.
• The so-called Elvis operator
• Conditionally invoke member operator

public static void Change(this String str, Action<String> change) {
	var length = str?.Length ?? 0;
 
	if (length > 0)
		change?.Invoke(str);
}
public static void ShowTargetWindow(String target) {
	if (target == null)
		throw new ArgumentNullException(nameof(target));
 
	return Assembly.GetExecutingAssembly().GetTypes().
	           Where(m => m.Name == target).
	           Select(m => m.GetConstructor(null).Invoke(null)).
	           OfType<Window>().FirstOrDefault()?.Show();
}

• Feel free to contact me

• Web: florian-rappl.de
• eMail: mail@florian-rappl.de
• Twitter: @FlorianRappl
• Google+: gplus.to/FlorianRappl

• Find the presentation at talks.florian-rappl.de/Cs6-in-30min.