c# 9 and .Net 5 are finally officially released, and everybody blogs about init-only properties and records - which are very exciting and long-awaited features that I'm sure will be used a lot and contribute a lot to code quality.
However, I would like to address another great thing about c# 9 that I didn't see a lot of bloggers excited about - and that is the improvements of pattern matching. Specifically, the adding of the not keyword - as it relates to an older post I've published almost exactly a year ago:
In c# 9, We finally actually do have the perfect non-null test, and it's way better than
x is object because it's much, much more readable:if(x is not null) { /* No explanation needed... */ }
See when I first started using x is object in my code, My team leader have complained that it's less readable than the x != null we had all over our code base. I actually had to convince him that this is a better option. With the c#9 new syntax, anyone reading the code that has even minimal knowledge of c# and the English language can instantly understand it - which finally, makes it truly the perfect non-null test.
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