Multi-paradigm programming language encompassing strong typing, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines
Beginning with C# 8.0 on .NET Core 3.0, you can define an implementation when you declare a member of an interface. The most common scenario is to safely add members to an interface already released and used by innumerable clients.
In this tutorial, you'll learn how to:
No doubts that async/await pattern has significantly simplified working with asynchronous operations in C#. However, this simplification relates only to the situation when asynchronous operations are executed consequently. If we need to execute several asynchronous operations simultaneously (e.g. we need to call several micro-services) then we do not have many built-in capabilities and most probably Task.WhenAll will be used:
Task<SomeType1> someAsyncOp1 = SomeAsyncOperation1();
Task<SomeType2> someAsyncOp2 = SomeAsyncOperation2();
Task<SomeType3> someAsyncOp3 = SomeAsyncOperation3();
Task<SomeType4> someAsyncOp4 = SomeAsyncOperation4();
await Task.WhenAll(someAsyncOp1, someAsyncOp2, someAsyncOp4);
var result = new SomeContainer(
someAsyncOp1.Result,someAsyncOp2.Result,someAsyncOp3.Result, someAsyncOp4.Result);This is a working solution, but it is quite verbose and not very reliable (you can forget to add a new task to “WhenAll”). I would prefer something like that instead:
var result = await
from r1 in SomeAsyncOperation1()
from r2 in SomeAsyncOperation2()
from r3 in SomeAsyncOperation3()
from r4 in SomeAsyncOperation4()
select new SomeContainer(r1, r2, r3, r4);Further I will tell you what is necessary for this construction to work...
I'm putting part of older WebForms portions of my site that still run on bare metal to ASP.NET Core and Azure App Services, and while I'm doing that I realized that I want to make sure my staging sites don't get indexed by Google/Bing.
I already have a robots.txt, but I want one that's specific to production and others that are specific to development or staging. I thought about a number of ways to solve this. I could have a static robots.txt and another robots-staging.txt and conditionally copy one over the other during my Azure DevOps CI/CD pipeline.
Then I realized the simplest possible thing would be to just make robots.txt be dynamic. I thought about writing custom middleware but that sounded like a hassle and more code that needed. I wanted to see just how simple this could be.
Today, we are announcing .NET Core 3.0 Preview 6. It includes updates for compiling assemblies for improved startup, optimizing applications for size with linker and EventPipe improvements. We’ve also released new Docker images for Alpine on ARM64.
Download .NET Core 3.0 Preview 6 right now on Windows, macOS and Linux.
Release notes have been published at dotnet/core. An API diff between Preview 5 and 6 is also available.
ASP.NET Core and EF Core are also releasing updates today.
If you missed it, check out the improvements we released in .NET Core 3.0 Preview 5, from last month.
I guess one of the most important issues in this topic is building an exception handling architecture in your application. This is interesting for many reasons. And the main reason, I think, is an apparent simplicity, which you don’t always know what to do with. All the basic constructs such as IEnumerable, IDisposable, IObservable, etc. have this property and use it everywhere. On the one hand, their simplicity tempts to use these constructs in different situations. On the other hand, they are full of traps which you might not get out. It is possible that looking at the amount of information we will cover you’ve got a question: what is so special about exceptional situations?
However, to make conclusions about building the architecture of exception classes we should learn some details about their classification. Because before building a system of types that would be clear for the user of code, a programmer should determine when to choose the type of error and when to catch or skip exceptions. So, let’s classify the exceptional situations (not the types of exceptions) based on various features.
QueryProvider can’t deal with this:
var result = _context.Humans
.Select(x => $"Name: {x.Name} Age: {x.Age}")
.Where(x => x != "")
.ToList();It can’t deal with any sentence using an interpolated string, but it’ll easily deal with this:
var result = _context.Humans
.Select(x => "Name " + x.Name + " Age " + x.Age)
.Where(x => x != "")
.ToList();The most painful thing is to fix bugs after turning on ClientEvaluation (exception for client-side calculation), since all Automapper profiles should be strictly analyzed for interpolation. Let’s find out what’s what and propose our solution to the problem.
It’s time to talk about exceptions or, rather, exceptional situations. Before we start, let’s look at the definition. What is an exceptional situation?
This is a situation that makes the execution of current or subsequent code incorrect. I mean different from how it was designed or intended. Such a situation compromises the integrity of an application or its part, e.g. an object. It brings the application into an extraordinary or exceptional state.
But why do we need to define this terminology? Because it will keep us in some boundaries. If we don’t follow the terminology, we can get too far from a designed concept which may result in many ambiguous situations. Let’s see some practical examples:
struct Number
{
public static Number Parse(string source)
{
// ...
if(!parsed)
{
throw new ParsingException();
}
// ...
}
public static bool TryParse(string source, out Number result)
{
// ..
return parsed;
}
}This example seems a little strange, and it is for a reason. I made this code slightly artificial to show the importance of problems appearing in it. First, let’s look at the Parse method. Why should it throw an exception?
var length = array.Length;
for (int i = 0; i < length; i++) {
//do smth
}
February 2019 marked the release of ReactiveUI 9 — the cross-platform framework for building GUI applications on the Microsoft .NET platform. ReactiveUI is a tool for tight integration of reactive extensions with the MVVM design pattern. You could familiarize yourself with the framework via a series of videos or the welcome page of the documentation. The ReactiveUI 9 update includes numerous fixes and improvements, but probably the most crucial and interesting one is integration with the DynamicData framework, allowing you to work with dynamic collections in Reactive fashion. Let’s find out what we can use DynamicData for and how this powerful reactive framework works under the hood!
With this newest Blazor release we’re pleased to announce that Blazor is now in official preview! Blazor is no longer experimental and we are committing to ship it as a supported web UI framework including support for running client-side in the browser on WebAssembly.
A little over a year ago we started the Blazor experimental project with the goal of building a client web UI framework based on .NET and WebAssembly. At the time Blazor was little more than a prototype and there were lots of open questions about the viability of running .NET in the browser. Since then we’ve shipped nine experimental Blazor releases addressing a variety of concerns including component model, data binding, event handling, routing, layouts, app size, hosting models, debugging, and tooling. We’re now at the point where we think Blazor is ready to take its next step.
Some days ago we announced improved Razor tooling support in Visual Studio Code with the latest C# extension. This latest release includes improved Razor diagnostics and support for tag helpers and Blazor apps.
