This compiles, but I get an error that it doesn't and the preview shows nothing. What am I missing?

Question

I've tried this with and without the apostrophe in the "I'm a machine" string, but neither of them work. This is getting really frustrating because nobody seems to be able to tell me exactly what's wrong or what I should do to fix it

robots.swift

class Point {
    var x: Int
    var y: Int

    init(x: Int, y: Int){
        self.x = x
        self.y = y
    }
}


class Machine {
    var location: Point

    init() {
        self.location = Point(x: 0, y: 0)
    }

    func move(direction: String) {
        print("Do nothing! Im a machine!") 
    }
}

// Enter your code below

class Robot: Machine {


    override init() {
        super.init()

    }



    override func move(direction: String) {
        switch direction{
            case "Up" : location.y += 1
            case "Down" : location.y -= 1
            case "Left" : location.x -= 1
            case "Right" : location.x += 1
        default : break
        }
    }
}

Answer 1 · 2017-02-02T14:39:00Z

February 2, 2017 2:39pm

Hey Jason,

Taking a look at the code provided in this challenge, the original move() method defined in Machine looks like this:

func move(_ direction: String) {
    print("Do nothing! I'm a machine!")
}

I was able to complete the challenge using your code by adding an underscore before the first argument in both the move method defined in Machine and the override method in Robot. The underscore tells the compiler that there should not be an argument label for the first parameter in the method.

It's the difference between calling the method like this:

func move(_ direction: String) {
    print("Do nothing! I'm a machine!")
}
move("Up")

and this:

func move(direction: String) {
    print("Do nothing! I'm a machine!")
}
move(direction: "Up")

I'll bet the test harnessed failed your code because you were requiring a label for the argument "direction".

Hope this helps!

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Jason Oliverson

Jason Oliverson

This compiles, but I get an error that it doesn't and the preview shows nothing. What am I missing?

1 Answer

Kevin Fricovsky

Kevin Fricovsky