Past exam of the year 1 of the computer science course of the University of Oxford / 2016 / Imperative programming / 6 / a

The output is 1, with no newline. The Any in class B[Any] and class C[Any] is a type parameter name that shadows the standard type scala.Any inside those class bodies. Renaming it to T preserves the program's meaning. Thus new B[Int] has an inherited m(Double) and its own m(Int); obj1.m(1) selects the latter and prints 1. The call with 2.3 can only use the inherited m(Double), which computes a sum without printing.

For new C[Any], the supplied type argument is the standard scala.Any, so the overloads are m(Double) and m(scala.Any). The more-specific Double alternative accepts 4 by numeric widening, and accepts 5.6 directly. Both return sums without printing. A computed result is not automatically screen output. This reasoning uses the Scala 2.11 overload conventions of Question 5(a); type erasure does not turn either class's generic-argument overload into an method overriding of m(Double).