6. Acreditamos que a diversidade, em
suas diversas expressões, deve ser
respeitada e valorizada, e que uma
sociedade mais diversa é uma
sociedade melhor.
diversidade.tech
21. public static int DiceSum(IEnumerable<object> values)
{
var sum = 0;
foreach (var item in values)
{
if (item is int val)
sum += val;
else if (item is IEnumerable<object> subList)
sum += DiceSum(subList);
}
return sum;
}
https://docs.microsoft.com/dotnet/csharp/pattern-matching
http://bit.ly/cspatternmatching
23. case 0:
break;
case int val:
sum += val;
break;
case PercentileDie die:
sum += die.Multiplier * die.Value;
break;
https://docs.microsoft.com/dotnet/csharp/pattern-matching
public static int DiceSum(IEnumerable<object> values)
{
var sum = 0;
foreach (var item in values)
{
switch (item)
{
}
}
return sum;
}
http://bit.ly/cspatternmatching
24. case 0:
break;
case int val:
sum += val;
break;
case PercentileDie die:
sum += die.Multiplier * die.Value;
break;
https://docs.microsoft.com/dotnet/csharp/pattern-matching
case IEnumerable<object> subList when subList.Any():
sum += DiceSum(subList);
break;
case IEnumerable<object> subList:
break;
case null:
break;
default:
throw new InvalidOperationException("unknown");
public static int DiceSum(IEnumerable<object> values)
{
var sum = 0;
foreach (var item in values)
{
switch (item)
{
}
}
return sum;
}
http://bit.ly/cspatternmatching
26. void M()
{
var (name, company) = Person.Get();
WriteLine($"{name}, {company}");
}
class Person
{
public string Name { get; set; }
public string Company { get; set; }
public void Deconstruct(out string name, out string company)
{
name = Name;
company = Company;
}
public static Person Get() => new Person { Name = "…", Company = "…" };
} https://docs.microsoft.com/dotnet/csharp/tupleshttp://bit.ly/cstuplas
27. var numbers = (one: 1, two: 2);
var (uno, due) = numbers;
WriteLine($"{uno}, {due}");
https://docs.microsoft.com/dotnet/csharp/tuples
http://bit.ly/cstuplas
28. if (int.TryParse("1", out int result))
WriteLine(result);
if (int.TryParse("1", out var result2))
WriteLine(result2);
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#out-variables
http://bit.ly/csoutvars
29. (int x, int y) GetCoordinates() => (1, 2);
var (_, y) = GetCoordinates();
https://docs.microsoft.com/dotnet/csharp/discards
http://bit.ly/csdiscards
31. if (int.TryParse("1", out _))
WriteLine("It is a number!");
https://docs.microsoft.com/dotnet/csharp/discards
http://bit.ly/csdiscards
32. object o = 1;
if (o is Person p)
WriteLine(p.Company);
else if (o is null)
WriteLine("null");
else if (o is var _)
WriteLine("Unknown");
https://docs.microsoft.com/dotnet/csharp/discards
http://bit.ly/csdiscards
33. ref int Find(int[,] matrix, Func<int, bool> predicate)
{
for (int i = 0; i < matrix.GetLength(0); i++)
for (int j = 0; j < matrix.GetLength(1); j++)
if (predicate(matrix[i, j]))
return ref matrix[i, j];
throw new InvalidOperationException("Not found");
}
void M()
{
var matrix = new [,] { { 1, 2, 3, 4, 5 }, { 6, 7, 8, 42, 10 } };
ref var item = ref Find(matrix, val => val == 42);
WriteLine(item);
item = 24;
WriteLine(matrix[1, 3]);
}
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#ref-locals-and-returns
http://bit.ly/csreflocals
34. public ExpressionBodiedMembers(string name) => Name = name;
~ExpressionBodiedMembers() => WriteLine("Finalized!");
private string name;
public string Name
{
get => name;
set => name = value;
}
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#more-expression-bodied-members
http://bit.ly/csmaisebm
35. private string a = GetA() ?? throw new Exception();
private static string GetA() => throw new Exception();
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#throw-expressions
http://bit.ly/csexpthrow
36. int sixteen = 0b0001_0000;
int thirtyTwo = 0b0010_0000;
int sixtyFour = 0b0100_0000;
int oneHundredTwentyEight = 0b1000_0000;
long oneHundredBillions = 100_000_000_000;
double AvogadroConstant = 6.022_140_857_747_474e23;
decimal GoldenRatio = 1.618_033_988_749M;
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#numeric-literal-syntax-improvements
http://bit.ly/csnumlit
37. double Average(IEnumerable<int> ns)
{
double Divide(double a, double b)
{
if (b == 0) throw new DivideByZeroException();
return a / b;
}
var sum = ns.Sum();
return Divide(sum, ns.Count());
}
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#local-functions
http://bit.ly/cslocalfunc
38. void Add1AndSumAll(int[] ms)
{
IEnumerable<int> Sum1(IEnumerable<int> ns)
{
foreach (var n in ns)
yield return n + 1;
}
if (ms == null) throw new NullReferenceException();
WriteLine(Sum1(ms).Sum());
}
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#local-functions
http://bit.ly/cslocalfunc
40. public async ValueTask<int> SumAsync(IEnumerable<ValueTask<int>> ns)
{
var sum = 0;
foreach (var nTask in ns)
{
var n = await nTask;
sum += n;
}
return sum;
}
https://docs.microsoft.com/dotnet/csharp/whats-new/csharp-7#generalized-async-return-types
http://bit.ly/csasyncgeneral
47. void M(int i, int j) { }
void N()
{
M(i: 2, 3);
}
https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.2/non-trailing-named-arguments.md
http://bit.ly/csntna
48. var m = 0b_101; //5
var n = 0x_00C0; // 192
https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.2/leading-separator.md
http://bit.ly/cs_num
49. class Base
{
private protected int f;
}
class DerivedInSameAssembly : Base
{
void M()
{
var x = base.f;
}
}
class DerivedInOtherAssembly : Base
{
void M()
{
var x = base.f; //error
}
}
https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.2/private-protected.md
http://bit.ly/csprpr
50. Vector Add(in Vector v1, in Vector v2)
{
v1 = default(Vector); // not OK!!
v1.X = 0; // not OK!!
Foo(ref v1.X); // not OK!!
// OK:
return new Vector(v1.X +v2.X, v1.Y + v2.Y);
}
https://docs.microsoft.com/dotnet/csharp/reference-semantics-with-value-types
http://bit.ly/csmodin
52. public static Ponto Subtrai(ref this Ponto p1, ref Ponto p2) =>
new Ponto(p1.X - p2.X, p1.Y - p2.Y);
void Ref()
{
Ponto p1 = new Ponto(1, 2), p2 = new Ponto(3, 4);
var pResultado = p1.Subtrai(ref p2);
p1.Subtrai(ref new Ponto()); // não compila
new Ponto().Subtrai(ref p1); // não compila
}
https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.2/readonly-ref.md#refin-extension-methods
http://bit.ly/csextref
54. ref readonly Vector FetchOrigin() => ref origin;
void M()
{
var v1 = new Vector(1, 2, 3);
var v2 = new Vector(4, 5, 6);
var vSum = Add(v1, v2);
ref readonly var origin = ref FetchOrigin();
}
private readonly Vector origin = new Vector(0, 0, 0);
https://docs.microsoft.com/dotnet/csharp/reference-semantics-with-value-types
http://bit.ly/csretrefro
55. ref readonly var origin = ref FetchOrigin();
var origin2 = FetchOrigin(); // copy created
https://docs.microsoft.com/dotnet/csharp/reference-semantics-with-value-types
http://bit.ly/csretrefro
56. readonly struct Ponto
{
public Ponto(float x, float y)
{
X = x;
Y = y;
}
public float X { get; }
public float Y { get; }
private readonly static Ponto origem = new Ponto();
public static ref readonly Ponto Origem => ref origem;
}
https://docs.microsoft.com/dotnet/csharp/reference-semantics-with-value-types#readonly-struct-type
http://bit.ly/csrostruct
57. ref readonly var p = ref Ponto.Origem;
var x = p.X; // sem cópia
https://docs.microsoft.com/dotnet/csharp/reference-semantics-with-value-types#readonly-struct-type
http://bit.ly/csrostruct
59. ref struct TwoSpans<T>
{
// pode ter campos desde que não sejam classes
public Span<T> first;
public Span<T> second;
}
// erro: arrays of ref-like types are not allowed.
TwoSpans<int>[] arr = null;
https://docs.microsoft.com/en-us/dotnet/csharp/reference-semantics-with-value-types#ref-struct-type
60. readonly ref struct ReadOnlyRefPoint2D
{
public int X { get; }
public int Y { get; }
public ReadOnlyRefPoint2D(int x, int y) =>
(X, Y) = (x, y);
}
https://docs.microsoft.com/dotnet/csharp/reference-semantics-with-value-types#readonly-ref-struct-type
61. void M()
{
Span<int> arr = stackalloc int[3];
}
https://msdn.microsoft.com/en-us/magazine/mt814808.aspx
Não é unsafe
63. Span<int> RowFive = new Span<int>(PascalsTriangle, 10, 5);
fixed (int* ptrToRow = RowFive)
{
// Soma os números 1,4,6,4,1
var sum = 0;
for (int i = 0; i < RowFive.Length; i++)
{
sum += *(ptrToRow + i);
}
Console.WriteLine(sum);
}
https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.3/pattern-based-fixed.md
int[] PascalsTriangle = {
1,
1, 1,
1, 2, 1,
1, 3, 3, 1,
1, 4, 6, 4, 1,
1, 5, 10, 10, 5, 1 };
Span<T>.GetPinnableReference()
64. unsafe struct S
{
public fixed int myFixedField[10];
}
class C
{
private static S s = new S();
unsafe public void M()
{
int p = s.myFixedField[5];
}
}
https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-7-3#indexing-fixed-fields-does-not-require-pinning
// CSharp 7.2
fixed (int* ptr = s.myFixedField)
{
int p = ptr[5];
}
65. var structs = new StructGrande[]
{ new StructGrande(), new StructGrande() };
ref StructGrande refLocal = ref structs[0];
refLocal = ref structs[1];
https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-7-3#ref-local-variables-may-be-reassigned
67. unsafe public static byte[] ToByteArray<T>
(this T argument) where T : unmanaged
{
var size = sizeof(T);
var result = new byte[size];
byte* p = (byte*)&argument;
for (var i = 0; i < size; i++)
result[i] = *p++;
return result;
}
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/generics/constraints-on-type-parameters#unmanaged-constraint
68. public static TDelegate TypeSafeCombine<TDelegate>
(this TDelegate source, TDelegate target)
where TDelegate : System.Delegate =>
System.Delegate.Combine(source, target)
as TDelegate;
Action first = () => Console.WriteLine("this");
Action second = () => Console.WriteLine("that");
var combined = first.TypeSafeCombine(second);
combined();
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/generics/constraints-on-type-parameters#delegate-constraints
69. public static Dictionary<int, string> EnumNamedValues<T>()
where T : System.Enum
{
var result = new Dictionary<int, string>();
var values = Enum.GetValues(typeof(T));
foreach (int item in values)
result.Add(item, Enum.GetName(typeof(T), item));
return result;
}
enum Rainbow { Red, Orange, Yellow, Green, Blue, Indigo, Violet }
var map = EnumNamedValues<Rainbow>();
foreach (var pair in map)
Console.WriteLine($"{pair.Key}:t{pair.Value}");
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/generics/constraints-on-type-parameters#enum-constraints
72. public class Foo
{
protected Foo(out int i) => i = 1;
}
public class Bar : Foo
{
public int Value { get; }
public Bar() : base(out int value) => Value = value;
}
https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.3/expression-variables-in-initializers.md
73. public class Baz
{
private readonly int field1 =
int.TryParse(SomeStatic.Text, out int value)
? Value
: -1;
}
https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.3/expression-variables-in-initializers.md
76. public class Cartesian { public int X { get; } public int Y { get; } }
public class Polar
{
public static bool operator is(Cartesian c, out double R, out double Theta)
{
R = Math.Sqrt(c.X * c.X + c.Y * c.Y);
Theta = Math.Atan2(c.Y, c.X);
return c.X != 0 || c.Y != 0;
}
}
void M()
{
var c = new Cartesian(3, 4);
if (c is Polar(var R, _)) WriteLine(R);
}
https://github.com/dotnet/csharplang/blob/master/proposals/patterns.md
77. void N(string? aNullableString, bool condition) {
WriteLine(aNullableString.Length); // warning
if (aNullableString != null)
WriteLine(aNullableString); // no warning
if (!string.IsNullOrWhiteSpace(aNullableString))
WriteLine(aNullableString!.Length); // I know better
var anotherNullableString = condition ? "Hello" : aNullableString;
WriteLine(anotherNullableString.Length); // warning
var yetAnotherNullableString = condition ? "Hello" : null;
WriteLine(yetAnotherNullableString.Length); // warning
string nonNullableString = null; //warning
WriteLine(nonNullableString); // no warning
}
https://github.com/dotnet/csharplang/blob/master/proposals/nullable-reference-types.md
https://github.com/dotnet/roslyn/blob/features/NullableReferenceTypes/docs/features/NullableReferenceTypes/README.md
78. async Task M()
{
foreach await (var i in GetStream())
WriteLine(i);
}
IAsyncEnumerable<int> GetStream() => new[] { 1, 2, 3 }.ToAsyncEnumerable();
async IAsyncEnumerable<int> MyIterator()
{
for (int i = 0; i < 100; i++)
{
await Task.Delay(1000);
yield return i;
}
}
https://github.com/dotnet/csharplang/blob/master/proposals/async-streams.md
79. using await (IAsyncDisposable resource = await store.GetRecordAsync(…)) { … }
class Foo : IAsyncDisposable
{
public async Task DisposeAsync()
{
await ...
}
}
https://github.com/dotnet/csharplang/blob/master/proposals/async-streams.md
80. interface I
{
void M() { WriteLine("I.M"); }
}
class C : I { } // OK
void M()
{ I i = new C();
i.M(); // prints "I.M"
}
https://github.com/dotnet/csharplang/blob/master/proposals/default-interface-methods.md
82. // list[Index.CreateFromEnd(1)]
var ultimoItem = list[^1];
// list[Index.CreateFromEnd(2)]
var penultimoItem = list[^2];
// list[3, Index.CreateFromEnd(2)]
var multiDimensional = list[3, ^2];
https://github.com/dotnet/csharplang/blob/master/proposals/ranges.md
83. // list[Range.Create(2, Index.CreateFromEnd(3))]
var slice1 = list[2..^3];
// list[Range.ToEnd(Index.CreateFromEnd(3))]
var slice2 = list[..^3];
// list[Range.FromStart(2)]
var slice3 = list[2..];
// list[Range.All]
var slice4 = list[..];
// list[Range.Create(1, 2), Range.All]
var multiDimensional = list[1..2, ..]
https://github.com/dotnet/csharplang/blob/master/proposals/ranges.md
84. class Person : IEquatable<Person>
{
public string First { get; }
public string Last { get; }
public Person(string First, string Last) => (this.First, this.Last) = (First, Last);
public void Deconstruct(out string First, out string Last)
=> (First, Last) = (this.First, this.Last);
public bool Equals(Person other)
=> other != null && First == other.First && Last == other.Last;
public override bool Equals(object obj) => obj is Person other ? Equals(other) : false;
public override int GetHashCode() => GreatHashFunction(First, Last);
…
}
class Person(string First, string Last);
https://github.com/dotnet/csharplang/blob/master/proposals/records.md
85. extension class Enrollee extends Person
{
// static field
static Dictionary<Person, Professor> enrollees = new Dictionary<Person, Professor>();
// instance method
public void Enroll(Professor supervisor) { enrollees[this] = supervisor; }
// instance property
public Professor Supervisor => enrollees.TryGetValue(this, out var supervisor) ? supervisor : null;
// static property
public static ICollection<Person> Students => enrollees.Keys;
// instance constructor
public Person(string name, Professor supervisor) : this(name) { this.Enroll(supervisor); }
}
https://github.com/dotnet/csharplang/issues/192
86. public shape SGroup<T>
{
static T operator +(T t1, T t2);
static T Zero { get; }
}
https://github.com/dotnet/csharplang/issues/164
87. public static AddAll<T>(T[] ts) where T : SGroup<T>
{
var result = T.Zero;
foreach (var t in ts) { result += t; }
return result;
}
https://github.com/dotnet/csharplang/issues/164
88. public shape SGroup<T>
{
static T operator +(T t1, T t2);
static T Zero { get; }
}
https://github.com/dotnet/csharplang/issues/164
89.
90. w w w. l a m b d a 3 . c o m . b r
Obrigado!
Giovanni Bassi
@giovannibassi
/giggio.tech
Notes de l'éditeur
field initializers, property initializers, constructor initializers, and query clauses
field initializers, property initializers, constructor initializers, and query clauses
field initializers, property initializers, constructor initializers, and query clauses
field initializers, property initializers, constructor initializers, and query clauses
