This blog post is part of The Third Annual C# Advent, a series of 50 posts about C#. Be sure to check out the rest of the blog posts in the calendar! If you have ever bound an ObservableCollection<T> to a WPF control, you know it's hard to add or remove items from multi-threads. Indeed, the UI expects the events to be raised on the UI thread. Also, you should not change the collection until the change…[read more]

While I prefer testing the public API of an assembly, it's sometimes useful to test the implementation details. So, an attribute that I often use is [assembly: InternalsVisibleTo("MyAssembly.Tests")] to allow the test assembly to use internal classes or methods. A convention is to declare assembly attribute in the file AssemblyInfo.cs. With the new SDK-based project, there is no AssemblyInfo.cs by default…[read more]

Tasks are very useful to start background work. You can use Task.Run(() => { ... }) to start a background operation. If the background operation succeeds, everything's good. If it fails, you check the task.Exception directly to know why it failed or you can await the task or use a blocking call such as Result or Wait() to get the exception. In this case you can handle the exception the way you want. If…[read more]

If you often works with JSON documents, you may have created classes to map the content of the JSON document to a .NET class. Then, Json.NET or the new System.Text.Json allow to serialize a class to a JSON string or to deserialize a JSON string to a .NET class. Writing mapping classes is annoying and error prone. Instead of writing them yourself, Visual Studio can generate them using a sample JSON string.…[read more]

When you write code, you sometimes need to read the documentation of a method or a class to understand how it works. The IntelliSense already provides useful information, but the documentation can contains useful remarks or links that you may need. You can open your favorite search engine and search for the name of the method. If you are lucky the first result is the link to the Microsoft documentation.…[read more]

Index and Range are 2 new types that support the new language features: hat and range operators. The ^ operator indicates the element position from the end of a sequence. For a sequence of length length, ^n points to the element with offset length - n from the start of a sequence. For example, ^1 points to the last element of a sequence and ^length points to the first element of a sequence. The ..…[read more]

When you first open a solution, you just want to press F5 to start debugging. If the solution contains multiple projects, you want the main project to be the startup project. You don't want the library project to be the startup project, but the web or desktop application. This provides a good development experience. Of course you can change the startup project manually using the context menu or the…[read more]

In the previous post, I've explained how to use Nullable Reference Types and why this is a good feature. However this feature works well only with .NET Core 3.0. Note that C# 8.0 is not meant for older targets, such as .NET Core 2.x or .NET Framework 4.x. So some additional language features may not work unless you are targeting .NET Core 3.0 or .NET Standard 2.1 It doesn't mean you cannot use it with…[read more]

In Visual Studio you can easily open a file using the search everything functionality (Ctrl+T). But for some operation, such as renaming a file, you need to find the file in the solution explorer. You can quickly locate the currently opened file in it using Ctrl+[, S or using the following button: You can also activate the option "Track Active Item in Solution Explorer" to automatically select the current…[read more]

In C#, a regex is just a string. When the pattern is not simple, it can be hard to understand it. Visual Studio 2019 comes with some improvements to help you working with regexes. Regex are colorized Each part of the pattern is colorized. It's easy to distinguish special characters, groups, quantifiers, comments, etc.: The colorization depends on the regex options: Autocompletion works inside the pattern…[read more]