10.7. Traits for Rich Interfaces

A trait can have many utility methods that depend on a few abstract ones. One example is the Scala Iterator trait that defines dozens of methods in terms of the abstract next and hasNext methods.

Let us enrich our rather anemic logging API. Usually, a logging API lets you specify a level for each log message to distinguish informational messages from warnings or errors. We can easily add this capability without forcing any policy for the destination of logging messages.