This code runs perfectly in Xcode. I don't know what I'm doing wrong with overriding

Question

I believe the linter is being oversensitive.

Button.swift

class Button {
    var width: Double
    var height: Double

    init(width:Double, height:Double){
        self.width = width
        self.height = height
    }

    func incrementBy(points: Double){
        width += points
        height += points
    }
}

class RoundButton: Button {
    var cornerRadius: Double = 5.0

    override func incrementBy(points: Double = 7.0){
        width += points
        height += points
    }

}

Answer 1 · 2015-10-24T15:00:49Z

October 24, 2015 3:00pm

Hi Paul,

Your solution is so close to being correct. In order to tackle the problem, lets take a look at the original implementation

class RoundButton: Button {
    var cornerRadius: Double = 5.0

    override func incrementBy(points: Double) {   // method signature
        width += points
        height += points
    }
}

//usage
let aRoundButton = RoundButton(width: 10.0, height: 10.0) 
aRoundButton.incrementBy(10)

The way the 'incrementBy' method achieves its objective is by accepting one argument (no external parameter name by default). When you introduce the default value for the parameter, you also introduce another scenario which is not passing anything.

aRoundButton.incrementBy()   // gives you an error about expecting a value

You want to tell the compiler, "hey I have a default value for my parameter, and I don't need anything there". In order to approach this, you simply just place the underscore in the place of the external parameter name.

class RoundButton: Button {
    var cornerRadius: Double = 5.0

    override func incrementBy(_ points: Double = 7.0) {   // method signature
        width += points
        height += points
    }
}

Hope I've helped. Happy Coding! :)

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asdfoh

asdfoh

This code runs perfectly in Xcode. I don't know what I'm doing wrong with overriding

1 Answer

Richard Lu

Richard Lu