Is there a reasonable approach to “default” type parameters in C# Generics?

Question

In C++ templates, one can specify that a certain type parameter is a default. I.e. unless explicitly specified, it will use type T.

Can this be done or approximated

Answer 1

C# does not support such a feature.

As you said, you can subclass it (if it's not sealed, and duplicate all constructor declarations) but it's a completely different thing.