ufcpp-live
commented
4 years ago 配信中に書き散らかした結果:
// new features in .NET 5 preview 4
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Runtime.InteropServices.ComTypes;
using System.Threading;
interface IA { int A(); }
interface IB : IA { int B(); }
interface IC : IA { int C(); }
class Ab : IB, IC
{
public int A() => 2;
public int B() => 3;
public int C() => 5;
}
class Program
{
static void Main()
{
Console.WriteLine(float.NaN == float.NaN); //false
//// native int
//nint i = 1;
//nint u = 2;
//Console.WriteLine(i + u);
}
// target-typed new
static Dictionary<string, int> d = new()
{
{ "a", 1 },
};
static void M1(object obj)
{
// !ReferenceEquals(obj, null)
if (obj is { }) // 知ってないと意味不明
{
}
// 同じ意味
if (obj is not null) // 初見さんにやさしい
{
}
// ユーザー定義の != があればそれを呼ぶ
if (obj != null)
{
}
IA a = obj is null
? (IA)null
: (IB)null;
int b1 = obj is null
? (byte)1
: (int)2;
int? c1 = obj is null
? (int?)null
: (int)2;
IA aa = obj switch
{
IB b => b,
IC c => c,
};
M((short)1, obj is null ? (int)1 : (short)2);
}
static void M(short x, short y) { }
static void M(int x, int y) { }
static void M<T>(T obj)
where T : IB, IC // and
{
obj.A();
obj.B();
obj.C();
}
//static void M<T>(T obj)
// where T : IB or IC // 要望はあり。別提案
//{
// obj.A();
// obj.B();
// obj.C();
//}
static int M11(object obj) => obj switch
{
byte => 1,
sbyte => 1,
ushort => 2,
short => 2,
int => 4,
uint => 4,
long => 8,
ulong => 8,
DateTime => 8,
DateTimeOffset => 16,
Guid => 16,
_ => -1,
};
static int M11(bool b) => b switch
{
true => 1,
false => 0,
};
class A { }
class B : A { }
class C : A { }
#nullable enable
// pattern V3 (and, or, not, simple type, parenthesized...)
static int M(object? obj) => obj switch
{
IB b and IC c => b.A() * b.B() * c.C(),
(IA or IB) and var a => a.A(),
//(B or C) and var a => a.A(), // object です(今のところ)。A にする提案あり
string s => s.Length,
//{ } a => a.GetHashCode(), // not null の意味含む(初見に厳しい)
not null and var a => a.GetHashCode(),
};
// pattern V3 (rerational, exhaustivity check)
static int M(float value) => value switch
{
< (10 * 10) => 1,
>= 100 and < 500 => 2,
5 * 100 => 5,
> 500 => 3,
float.NaN => 4,
//_ => 2,
};
static int M111(float value) => value switch
{
var x when x < 100 => 1,
var x when x >= 100 && x <= 500 => 2,
var x when x > 500 => 3,
};
// pattern V3 (byte exhaustivity check)
static int M(byte ascii) => ascii switch
{
<= 31 => 0, // control
32 => 2, // white space
<= 47 => 3, // symbol
<= 57 => 4, // number
<= 64 => 3, // symbol
>= (int)'A' and <= (int)'Z' => 5, // letter A-Z
>= (int)'a' and <= (int)'z' => 5, // letter a-z
> (int)'z' and <= 126 => 3,
127 => 0,
>= 128 => 6, // non-asci
};
}
Microsoft Build に合わせていろいろとブログ公開が。
追記: C# チームも1日遅れでブログ出した
正直、ブログ読みふけってて Build のキーノート(ブチザッキ参照)全然聞いてない。
1回の配信で触れる量じゃないし、とりあえずC# 9.0 の話を中心に(他はチャットの反応次第)。
C# 9.0: