Comparing strings is different from comparing numbers. 2 numbers are equal if their values are identical. For instance 1 is equal to 1, and 1 is not equal to 2. That's trivial. When it comes to string, things are different. For instance, do you want a case-sensitive comparison? What about the different ways to write the same letter. For instance, the letter ß is common in German, but it's also possible to… [read more]

I've created a pull request on the ASP.NET Core repository. At the beginning, the changes were just about changing the unsafe code (char*) for stackalloc to a safe version with Span. So, it was a very small change. During the review, Oleksandr Kolomiiets, Günther Foidl, and David Fowler have suggested a few additional changes to improve the performance. Thank you very much for taking the time to review… [read more]

Creating automated tests is important to be sure your application behaves as it should. The more tests you write, the more use cases are covered. Sometimes it can be hard to know which parts of the application are well tested, and which ones are not. That's why code coverage is interesting. It can be a useful measure to detect potential risk areas in the application (i.e. the most complex methods with the… [read more]

When creating a Roslyn analyzer, you almost always have to work with types. For instance, you may want to find an argument of a specific type or check if a method is declared on a specific type. For instance, your analyzer may need to answer the following question: What is the type of the sample in var sample = new Test();? Or does the Test class has a constructor with a CancellationToken parameter? To… [read more]

In a previous blog post, I explained how to write a Roslyn Analyzer for C#. This analyzer uses the C# syntax tree and the semantic model to detect some patterns and reports warnings. Then, the code fix can replace nodes in the C# syntax tree. So, the analyzer cannot be used for VB.NET as the syntax tree is different. This means you would need to create and maintain an analyzer for C# and another one for… [read more]

In a previous post, I've talked about inlining a CSS file in the html page. In term of performance, this is important to inline the critical CSS. However, the rest of the styles of the page doesn't need to be downloaded immediately. For script elements, you can simply add the attribute async to instruct the browser to load the resource asynchronously. For stylesheets, there is no equivalent. You have to… [read more]

This blog post is part of The Second C# Advent Calendar, a series of 50 posts about C#. Be sure to check out the rest of the blog posts in the calendar! Roslyn is the C# and VB.NET compiler. Roslyn also provides language services that can be used by IDE such as refactorings, code fixes, or edit and continue. If you are not familiar with Roslyn, you should read the following post to discover the scope of… [read more]

In the previous post, I've written about inlining a Stylesheet file in the page. This allow you to reduce the number of requests required to load the page, and so to reduce the loading time of the page. The TagHelper automatically replace the tag by the content of the file at runtime, so the html document stays clean in the source code. In this post, we'll create new Tag Helpers to be able to inline CSS,… [read more]

When you have a very tiny stylesheet, it may be more performant to inline it directly in the page. Indeed, it will avoid one network call, and the layout may be blocked until the browser get the response of this call. If the stylesheet is very small you may not care about caching the file on the client. For instance, on this website, the main stylesheet is 2kB large, and the full page with the inlined… [read more]

Integrating Google Analytics in your website is not very complicated. You just need to copy the snippet in the head tag of your page. But, there are another way to integrate it. Since ASP.NET Core 2.0, you can create a Tag Helper Component. A Tag Helper Component is a Tag Helper that allows you to conditionally modify or add HTML elements from server-side code. This allows you, for instance, to add some… [read more]