csharp6-presentation
csharp6-presentation
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csharp6-presentation
What's new in C# 6.0 presentationOn Github RaYell / csharp6-presentation
What's new in C# 6.0
Created by Lukasz Rajchel
24.11.2014
What's going on in .NET?
-
.NET fully open source
-
Mono support (partial but official)
-
Codename "Roslyn" - .NET compiler written in .NET
-
ASP.NET WebAPI & MVC architecture independent of System.Web & IIS
Work in progress
The features presented here can change before final version is released
Only selected new/updated features are part of this presentation
Syntactic sugar
Primary constructors
Old way
public class Point
{
public int _x;
public int _y;
public int _z;
public Person(int x, int y)
{
this._x = x;
this._y = y;
}
public Person(int x, int y, int z) : this(x, y)
{
this._z = z;
}
}
Primary constructors
New way
public class Point(int x, int y)
{
public int _x = x;
public int _y = y;
public int _z;
public Person(int x, int y, int z) : this(x, y)
{
this._z = z;
}
}
Auto property initializers
Old way
public class Reservation
{
public Reservation(string number)
{
this.Number = number;
this.CreatedDate = DateTime.Now;
}
public DateTime CreatedDate { get; private set; }
public string Number { get; private set; }
public string User
{
get { return Principal.WindowsPrincipal.Current.Identity.Name; }
}
}
Auto property initializers
New way
public class Reservation(string number)
{
public DateTime CreatedDate { get; private set; } = DateTime.Now;
public string Number { get; private set; } = number;
public string User { get; } = Principal.WindowsPrincipal.Current.Identity.Name;
}
Using statement for static members
Old way
using System;
Console.WriteLine("...");
Console.ReadLine();
New way
using System.Console;
WriteLine("...");
ReadLine();
Null-conditional operator
Old way
public string GetFieldText(Model model)
{
if (model == null)
{
return null;
}
var field = model.GetField();
if (field == null)
{
return null;
}
return field.Text;
}
New way
public string GetFieldText(Model model)
{
return model?.GetField()?.Text;
}
Declaration expressions
& out-type inference
Old way
int parseResult;
if (int.TryParse(parameter, out parseResult))
{
// ...
}
New way
if (int.TryParse(parameter, out int parseResult))
{
// ...
}
or
if (int.TryParse(parameter, out var parseResult))
{
// ...
}
Expression bodied
methods & properties
Old way
public string Text
{
get { return string.Format("{0} {1}", this.Process, this.Message); }
}
public override ToString()
{
return string.Format("{0} {1}", this.FirstName, this.LastName);
}
New way
public string Text => string.Format("{0} {1}", this.Process, this.Message)
public override ToString() =>
string.Format("{0} {1}", this.FirstName, this.LastName);
New features
Exception filters
Old way
try
{
DoSomething();
}
catch (Exception ex)
{
if (ex.Message.Contains("Fatal"))
{
Console.WriteLine("Fatal Exception");
}
else
{
throw;
}
}
Exception filters
New way
try
{
DoSomething();
}
catch (Exception ex) if (ex.Message.Contains("Fatal"))
{
Console.WriteLine("Fatal Exception");
}
Await in catch/finally blocks
Old way
try
{
await DoSomething();
}
catch (Exception ex)
{
await LogService.Error("Exception", ex); // compiler error
throw;
}
finally
{
await Logservice.Info("Finished"); // compiler error
}
Await in catch/finally blocks
Old way
ExceptionDispatchInfo capturedException = null;
try
{
await DoSomething();
}
catch (Exception ex)
{
capturedException = ExceptionDispatchInfo.Capture(ex);
}
if (capturedException != null)
{
await LogService.Error("Exception", capturedException.SourceException);
await LogService.Info("Finished"); // simulates finally
capturedException.Throw();
}
await LogService.Info("Finished"); // simulates finally
Await in catch/finally blocks
New way
try
{
await DoSomething();
}
catch (Exception ex)
{
await LogService.Error("Exception", ex);
throw;
}
finally
{
await Logservice.Info("Finished");
}
nameof expressions
Old way
public void Check(Person person)
{
if (person == null)
{
throw new ArgumentNullException("person");
}
}
or
public void Check(Person person)
{
if (person == null)
{
throw new ArgumentNullException(GetVariableName(() => person));
}
}
private static string GetVariableName<T>(Expression<Func<T>> expr)
{
var body = (MemberExpression)expr.Body;
return body.Member.Name;
}
nameof expressions
New way
public void Check(Person person)
{
if (person == null)
{
throw new ArgumentNullException(nameof(person));
}
}
And even more...
Want to learn more?
-
Check the C# Language Design Notes
-
Play with the Visual Studio 2015 Preview on a virtual machine