Today I will write about the way variance influences type checking in C#. Yes, the fact that one type can be passed to a generic method that requires another type, depends on these 2 small keywords we write before ‘T’ (or whatever 😉) in interface header.

Sometimes it happens that we use mechanisms/features of specific language without beeing aware of it. That’s fine, but if you’ll want to discuss your code in a future to the audience or coworkers, soon or later you’ll be forced to learn it and understand (or at least name it using technical nomenclature). Therefore, today I’m going to discuss two related „mechanisms” of C# which are covariance and contravariance.  Covariance Covariance is a type conversion from the specific type to the more general (ba...