explore what's new in C# 8, as well as what we can expect in the near (and far) future of C#!
We'll talk about:
- News in C# 8
- Pattern Matching (incl. Record Types)
- Nullable Reference Types and How to Avoid Null Reference Exceptions
- How Async & Await is Improving
// ... builder.Services.AddRazorComponents().AddInteractiveServerComponents(); // ... app.MapRazorComponents<App>().AddInteractiveServerRenderMode();
// ... builder.Services.AddRazorComponents(); // ... app.MapRazorComponents<App>();
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<base href="/" />
<link rel="stylesheet" href="bootstrap/bootstrap.min.css" />
<link rel="stylesheet" href="app.css" />
<link rel="stylesheet" href="MyApp.styles.css" />
<link rel="icon" type="image/png" href="favicon.png" />
<HeadOutlet />
</head>
<body>
<Routes />
<script src="_framework/blazor.web.js"></script>
</body>
</html> <Router AppAssembly="@typeof(Program).Assembly">
<Found Context="routeData">
<RouteView RouteData="@routeData" DefaultLayout="@typeof(Layout.MainLayout)" />
<FocusOnNavigate RouteData="@routeData" Selector="h1" />
</Found>
</Router> app.UseStatusCodePagesWithRedirects("/StatusCode/{0}"); @page "/StatusCode/{responseCode}"
<h3>StatusCode @ResponseCode</h3>
@code {
[Parameter] public string? ResponseCode { get; set; }
} if (!app.Environment.IsDevelopment())
{
app.UseExceptionHandler("/Error", createScopeForErrors: true);
} 404.razor
@page "/StatusCode/404" <PageTitle>Not found</PageTitle> <h1>Not found</h1> <p role="alert">Sorry, there's nothing at this address.</p>
500.razor
@page "/StatusCode/500" <PageTitle>Unexpected error</PageTitle> <h1>Unexpected error</h1> <p role="alert">There was an unexpected error.</p>
401.razor
@page "/StatusCode/401" <PageTitle>Not Authorized</PageTitle> <h1>Not Authorized</h1> <p role="alert">Sorry, you are not authorized to access this page.</p>
<HeadOutlet @rendermode="@InteractiveServer" /> ... <Routes @rendermode="@InteractiveServer" />
dotnet new blazor --interactivity Server --all-interactive
@rendermode InteractiveServerRenderModeWithoutPrerendering
@code{
static readonly IComponentRenderMode InteractiveServerRenderModeWithoutPrerendering =
new InteractiveServerRenderMode(false);
} | Check | Code | Description |
| Is Null | if(variable is null) return true; |
|
| Is Not Null | if(variable is { }) return false |
|
| Is Not Null | if(variable is object) return false |
|
| Is Null | if(variable == null) return true |
|
| Is Not Null | if(variable != null) return false |
|
These are the customer-reported issues addressed in this release:
This syntax supports static analysis such that later code will know whether variable is null or not.
Doesn’t produce a warning even when comparing against a non-nullable value type making the code to check pointless.
Requires C# 7.0 because it leverages type pattern matching.
git tags. CVE-2018-0875: Microsoft is aware of a security vulnerability in the public versions of .NET Core where a malicious file or web request could cause a denial of service (DoS) attack.
حجم تقریبی بروزرسانی از نسخه 15.6.1 به 15.6.2 برابر 1.2GB میباشد
Today we're thrilled to announce the release of ASP.NET Core 2.1.0! This is the latest release of our open-source and cross-platform web framework for .NET and it's now ready for production use.
@* For being rendered on the server *@ <Counter @rendermode="@InteractiveServer" /> @* For running in WebAssembly *@ <Counter @rendermode="@InteractiveWebAssembly" />
@rendermode InteractiveServer @rendermode InteractiveWebAssembly
<Counter @rendermode="@InteractiveAuto" />
@attribute [StreamRendering(prerender: true)]
interface ILogger
{
void Log(string message);
}
class ConsoleLogger : ILogger
{
public void Log(string message)
{
Console.WriteLine(message);
}
} interface ILogger
{
void Log(string message);
void Log(Exception exception) => Console.WriteLine(exception);
} interface IDeveloper
{
void LearnNewLanguage(string language, DateTime dueDate);
void LearnNewLanguage(string language)
{
// default implementation
LearnNewLanguage(language, DateTime.Now.AddMonths(6));
}
}
class BackendDev : IDeveloper // compiles OK
{
public void LearnNewLanguage(string language, DateTime dueDate)
{
// Learning new language...
}
} IDeveloper dev1 = new BackendDev();
dev1.LearnNewLanguage("Rust");
var dev2 = new BackendDev();
dev2.LearnNewLanguage("Rust");
There is no argument given that corresponds to the required formal parameter 'dueDate' of 'BackendDev.LearnNewLanguage(string, DateTime)' (CS7036) [ConsoleApp]
using System;
namespace ConsoleApp
{
public interface IDev
{
void LearnNewLanguage(string language) => Console.Write($"Learning {language} in a default way.");
}
public interface IBackendDev : IDev
{
void LearnNewLanguage(string language) => Console.Write($"Learning {language} in a backend way.");
}
public interface IFrontendDev : IDev
{
void LearnNewLanguage(string language) => Console.Write($"Learning {language} in a frontend way.");
}
public interface IFullStackDev : IBackendDev, IFrontendDev { }
public class Dev : IFullStackDev { }
} IFullStackDev dev = new Dev();
dev.LearnNewLanguage("TypeScript"); The call is ambiguous between the following methods or properties: 'IBackendDev.LearnNewLanguage(string)' and 'IFrontendDev.LearnNewLanguage(string)' (CS0121)
namespace MyNamespace
{
public interface IMyInterface
{
IList<int> Values { get; set; }
}
public static class MyInterfaceExtensions
{
public static int CountGreaterThan(this IMyInterface myInterface, int threshold)
{
return myInterface.Values?.Where(p => p > threshold).Count() ?? 0;
}
}
} var myImplementation = new MyInterfaceImplementation(); // Note that there's no typecast to IMyInterface required var countGreaterThanFive = myImplementation.CountGreaterThan(5);
public struct Statement
{
public int Id { get; }
public string Description { get; }
public Statement(int id, string description) => (Id, Description) = (id, description);
public override string ToString() => Description;
}
public static async Task<IEnumerable<Statement>> GetStatements(bool error)
{
if (error)
{
throw new Exception("Oops, we messed up 😬");
}
await Task.Delay(1000); //Simulate waiting for data to come through.
yield return new Statement(1, "C# is cool!");
yield return new Statement(2, "C# orginally named COOL.");
yield return new Statement(3, "More examples...");
} The body of 'AsyncStreams.GetStatements(bool)' cannot be an iterator block because 'Task<IEnumerable<AsyncStreams.Statement>>' is not an iterator interface type (CS1624)
static async IAsyncEnumerable<Statement> GetStatements(bool error)
static async IAsyncEnumerable<Statement> GetStatementsAsync(bool error)
{
await foreach (var statement in GetStatements(error))
{
await Task.Delay(1000);
yield return statement;
}
} using System.Threading;
namespace System.Collections.Generic
{
public interface IAsyncEnumerable<out T>
{
IAsyncEnumerator<T> GetAsyncEnumerator(CancellationToken cancellationToken = default);
}
public interface IAsyncEnumerator<out T> : IAsyncDisposable
{
T Current { get; }
ValueTask<bool> MoveNextAsync();
}
}
namespace System
{
public interface IAsyncDisposable
{
ValueTask DisposeAsync();
}
} public class AwaitUsingTest : IAsyncDisposable
{
public async ValueTask DisposeAsync()
{
await Task.CompletedTask;
}
public void Dummy() { }
} async Task FooBar()
{
await using var test = new AwaitUsingTest();
test.Dummy();
} dotnet new blazor --interactivity Server
dotnet new blazor --interactivity WebAssembly
// ...
builder.Services.AddRazorComponents()
.AddInteractiveServerComponents();
// ...
app.MapRazorComponents<App>()
.AddInteractiveServerRenderMode(); // ...
builder.Services.AddRazorComponents()
.AddInteractiveWebAssemblyComponents();
// ...
app.MapRazorComponents<App>()
.AddInteractiveWebAssemblyRenderMode()
.AddAdditionalAssemblies(typeof(Counter).Assembly); 
<Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly">
<PropertyGroup>
<TargetFramework>net8.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<ProjectReference Include="..\BlazorDemoApp.Shared\BlazorDemoApp.Shared.csproj" />
</ItemGroup>
</Project> builder.Services.AddScoped<IProductStore, ProductStore>();
@using static Microsoft.AspNetCore.Components.Web.RenderMode // ... @using BlazorDemoApp.Client.Components.Store @using BlazorDemoApp.Client.Components
<RelatedProducts ProductId="ProductId" @rendermode="@InteractiveWebAssembly"/>
using BlazorDemoApp.Services;
using Microsoft.AspNetCore.Mvc;
namespace BlazorDemoApp.Controllers;
[ApiController]
[Route("/api/[controller]")]
public class ProductsController : ControllerBase
{
private readonly IProductStore _store;
public ProductsController(IProductStore store) => _store = store;
[HttpGet("[action]")]
public IActionResult Related([FromQuery] int productId) => Ok(_store.GetRelatedProducts(productId));
} builder.Services.AddControllers(); // ... app.MapControllers();
@using BlazorDemoApp.Shared.Models
@inject HttpClient Http
<button class="btn btn-outline-secondary" @onclick="LoadRelatedProducts">Related products</button>
@if (_loadRelatedProducts)
{
@if (_relatedProducts == null)
{
<p>Loading...</p>
}
else
{
<div class="mt-3">
@foreach (var item in _relatedProducts)
{
<a href="/ProductDetails/@item.Id">
<div class="col-sm">
<h5 class="mt-0">@item.Title (@item.Price.ToString("C"))</h5>
</div>
</a>
}
</div>
}
}
@code{
private IList<Product>? _relatedProducts;
private bool _loadRelatedProducts;
[Parameter]
public int ProductId { get; set; }
private async Task LoadRelatedProducts()
{
_loadRelatedProducts = true;
var uri = $"/api/products/related?productId={ProductId}";
_relatedProducts = await Http.GetFromJsonAsync<IList<Product>>(uri);
}
} System.InvalidOperationException: Cannot provide a value for property 'Http' on type 'RelatedProducts'. There is no registered service of type 'System.Net.Http.HttpClient'.
<RelatedProducts ProductId="ProductId" @rendermode="@InteractiveWebAssembly"/>
builder.Services.AddScoped(sp => new HttpClient
{
BaseAddress = new Uri("http://localhost/")
}); using BlazorDemoApp.Shared.Models;
namespace BlazorDemoApp.Shared.Data;
public interface IProductStore
{
IList<Product> GetAllProducts();
Product GetProduct(int id);
Task<IList<Product>?> GetRelatedProducts(int productId);
} public Task<IList<Product>?> GetRelatedProducts(int productId)
{
var product = ProductsDataSource.Single(x => x.Id == productId);
return Task.FromResult<IList<Product>?>(ProductsDataSource.Where(p => product.Related.Contains(p.Id))
.ToList());
} [HttpGet("[action]")]
public async Task<IActionResult> Related([FromQuery] int productId) =>
Ok(await _store.GetRelatedProducts(productId)); public class ClientProductStore : IProductStore
{
private readonly HttpClient _httpClient;
public ClientProductStore(HttpClient httpClient) => _httpClient = httpClient;
public IList<Product> GetAllProducts() => throw new NotImplementedException();
public Product GetProduct(int id) => throw new NotImplementedException();
public Task<IList<Product>?> GetRelatedProducts(int productId) =>
_httpClient.GetFromJsonAsync<IList<Product>>($"/api/products/related?productId={productId}");
} builder.Services.AddScoped<IProductStore, ClientProductStore>();
builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) }); @inject IProductStore ProductStore
private async Task LoadRelatedProducts()
{
_loadRelatedProducts = true;
_relatedProducts = await ProductStore.GetRelatedProducts(ProductId);
} 
This is the final release candidate (RC) for .NET 7 and is supported in production.
