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

Inheritance

Inheritance lets one class build on another. A class declared with is after its name inherits the attributes and methods of the class it names — its parent (or base) class.

class Animal {
    has $.name;
    method speak {
        'some sound';
    }
}

class Dog is Animal {
}

Dog is Animal means a Dog is a kind of Animal. Without writing anything new, Dog already has the name attribute and the speak method from Animal:

my $rex = Dog.new(name => 'Rex');
say $rex.name;  # Rex
say $rex.speak; # some sound

A Dog object is also recognised as an Animal:

say Dog.new ~~ Animal; # True

The smart-match ~~ against a type is true when the object is of that type or inherits from it. The next topic shows how a child class can replace an inherited method with its own version.

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