Course of Raku / Objects, I/O, and exceptions / Classes and objects / Methods / Exercises / A walking robot

Solution: A walking robot

Here is a possible solution to the task.

Code

class Robot {
    has $.position is rw = 0;

    method move($steps = 1) {
        $.position += $steps;
    }
}

my $r = Robot.new;
$r.move(5);
$r.move;
$r.move(2);

say $r.position;

🦋 You can find the source code in the file bank-account.raku.

Output

8

Comments

1. The position attribute is is rw so that the method can change it, and it defaults to 0 so a fresh robot starts at the origin.

2. The move method gives its parameter a default value, $steps = 1. The bare call $r.move therefore advances by one step, while $r.move(5) and $r.move(2) advance by the amount given. The three calls add 5 + 1 + 2, so the final position is 8.

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