class NamedShape {
    var numberOfSides: Int = 0
    var name: String

    init(name: String) {
        self.name = name
    }

    func simpleDescription() -> String {
        return "A shape with \(numberOfSides) sides."
    }
}

class Circle: NamedShape {
    var radius: Double

    init(radius: Double, name: String) {
        self.radius = radius
        super.init(name: name)
    }

    var area: Double {
        get {
            return Double.pi * pow(radius, 2)
        }
        set {
            radius = sqrt(area / Double.pi)
        }
    }

    override func simpleDescription() -> String {
        return "A circle with radius \(radius)"
    }
}

let test = Circle(radius: Double(10), name: "my test circle")

test.area
test.simpleDescription()
test.area = 90
test.radius // shouldn't this set radius to a new value? the playground is still returning 10