Protocol
Potocol
Description
The idea here is to have a "set of methods". So, you can test a *class* based on that set of methods. But different from *roles* with stubbed methods it doesn't need do be "*does*ed" to be matched. It does create a subset but using a different syntax, and will check the methods.
Synopsis
use Protocol;
protocol Writer {               # creates a Writer protocol that have a write method
    method write { ... }
}
sub write(Writer $w) {          # accepts a Writer
    $w.write
}
class JustAGreeter {            # no roles, parents nor protocols declared on the class
    method write {              # it has the write method, so it attends to the protocol
        say "Hello protocol!"
    }
}
write JustAGreeter.new;         # prints: Hello protocol!