2003- C# 1.2 major .
,
roslyn github, 7.1 7.2.
, 7.1 pre-release Visual Studio.
.
.
Main ( 7.1)
, .
Main void int. . :
public static Task Main();
public static Task Main();
public static Task Main(string[] args);
public static Task Main(string[] args);
CLR entrypoints, boilerplate code ( - , void Task)
:
async Task Main(string[] args) {
// -
}
//
int $GeneratedMain(string[] args) {
return Main(args).GetAwaiter().GetResult();
}
7- .
default ( 7.1)
Visual Basic C# . .
C# null, VB.NET Nothing. , Nothing , . , null . , null.
default(T).
. , , :
void SomeMethod(string[] args)
{
}
:
SomeMethod(default(string[]));
default(string[]), default?
, C# 7.1 default.
, ?
, :
void SomeMethod(string[] args = default)
{
}
:
int i = default;
:
int i = 1;
if (i == default) { } // int 0
if (i is default) { } //
? default :
const int? y = default;
if (default == default)
if (default is T) // is default
var i = default
throw default
default as int; // 'as' reference
Readonly ref ( 7.2)
by value ( ) , . . ref , , . vector matrix.
:
static Vector3 Add (ref readonly Vector3 v1, ref readonly Vector3 v2)
{
// !
v1 = default(Vector3);
// !
v1.X = 0;
// !
foo(ref v1.X);
//
return new Vector3(v1.X +v2.X, v1.Y + v2.Y, v1.Z + v2.Z);
}
, .
in ref readonly
static Vector3 Add (in Vector3 v1, in Vector3 v2)
{
return new Vector3(v1.X +v2.X, v1.Y + v2.Y, v1.Z + v2.Z);
}
in, ref readonly ? in .
( 8.0)
.
, - , . (!) .
.
Java 8 , C# .
API .
.
SomeMethod :
interface IA
{
void SomeMethod() { WriteLine(" SomeMethod IA"); }
}
, :
class C : IA { }
:
IA i = new C();
SomeMethod:
i.SomeMethod(); // " SomeMethod IA"
( 7.1)
. .
:
, (f1: x.f1, f2: x?.f2) (x.f1, x?.f2).
f1, f2
( item1, item2 ...)
LINQ
// c result f1 f2
var result = list.Select(c => (c.f1, c.f2)).Where(t => t.f2 == 1);
C# 7.0. :
Action y = () => M();
var t = (x: x, y);
t.y(); // extension method y(),
, 7.0 7.1 .
, Visual Studio 7.0 ,
Tuple element name 'y' is inferred. Please use language version 7.1 or greater to access an element by its inferred name.
:
class Program
{
static void Main(string[] args)
{
string x = "demo";
Action y = () => M();
var t = (x: x, y);
t.y(); // extension method y(),
}
private static void M()
{
Console.WriteLine("M");
}
}
public static class MyExtensions
{
public static void y(this (string s, Action a) tu)
{
Console.WriteLine("extension method");
}
}
.NET 4.6.2 , NuGet System.ValueTuple
https://habrahabr.ru/post/331554/
