What is the return _ in C#
If you are not using the parameter in a lambda, people use _
as a convention for indicating that.
In your code, it is the catchall case for if serviceType
isn't resolved to a call site. Since you don't care about the serviceType
to return null, _
is used for that parameter.
This is probably a duplicate of this post which has lots of info:
C# style: Lambdas, _ => or x =>?
_ is a valid C# identifier, so _ => null
is the same as myServiceProvider => null
Defining what is a valid identifier is not as simple as checking the characters for a white list of allowed characters, but it's documented here