I'vealready made some posts about pattern matching, with the last one about positional pattern matching. Pattern matching made it possible to do a type check, cast to that checked type into a variable and then deconstruct its properties into variables:

if (person is Elf(int age, string elfishName))
            {
                Console.WriteLine($"Elf with elfish name{elfishName} is {age} years old");
            }

And it made it also possible to do a value check while deconstructing:

if (person is Elf(110, string elfishName))
            {
                Console.WriteLine($"Elf with elfish name{elfishName} is 110 years old");
            }

One of the drawbacks of this technique is that a deconstructor is needed (more about that in my blogpost about object deconstructing). Luckely for us, C# 8.0 provides us with property pattern matching!

What is it?

Well property pattern matching does the same as positional pattern matching but without the need of a _Deconstructor_ . The code above, which checks if the person is an Elf then deconstructs it and checks if his/her age is 110, looks like this with property pattern matching:

if (person is Elf{ Age: 110, ElfishName: var elfishName })
            {
                Console.WriteLine($"Elf with elfish name{elfishName} is 110 years old");
            }

As you can see, the syntax is quite similar to its counterpart. The downside however, is that it is more (computationally) expensive.

Sources

https://docs.microsoft.com/en-us/dotnet/csharp/deconstruct
Demo project: https://bitbucket.org/aldhaenens/p-d-demo/src/master/