100. Traits and interfaces

As Groovy’s interfaces don’t support default implementations it may be tempting to favour traits. This isn’t a good idea and you should try to describe interactions within your code and with other developers via an API described in interfaces.

Once you’ve described your interface, a trait can implement the interface in the same manner as classes do, through the use of the implements keyword:

interface Locomotion {
    String getDescription()
}

trait Hopping implements Locomotion {
    @Override
    String getDescription() {
        'hop hop hop'
    }
}