Course of Raku / Objects, I/O, and exceptions / Classes and objects / Roles

Composing several roles

A class can do more than one role. You simply list each one with its own does:

role Walk {
    method move { 'walking' }
}

role Swim {
    method dive { 'diving' }
}

class Duck does Walk does Swim {
}

The Duck class now has both the move method from Walk and the dive method from Swim:

say Duck.new.move; # walking
say Duck.new.dive; # diving

Combining roles like this is called composition. It lets you assemble a class from several independent pieces of behaviour, which is often more flexible than building a single chain of inheritance — a class can mix in exactly the capabilities it needs, and nothing more.

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Composing several roles

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