why is it return(price, color) instead of return (price, carpetColor) I don't understand

Question

func carpetCostHaving(length: Int, width: Int, carpetColor color: String = "tan") -> (price: Int, carpetColor: String) {
    //gray carpet - $1 per sq ft
    //tan carpet - $2 per sq ft
    //deep blue carpet - $4 per sq ft

    let areaOfRoom = area(length: length, width: width)

    var price = 0

    switch color {
    case "gray": price = areaOfRoom * 1
    case "tan": price = areaOfRoom * 2
    case "blue": price = areaOfRoom * 4
    default:
        price = 0
    }

    return(price,color)
}

let result = carpetCostHaving(length: 4, width: 12, carpetColor: "gray")

Answer 1 · 2018-04-09T18:51:53Z

April 9, 2018 6:51pm

You're using color in switch and returning color because you've defined a local argument name and an external argument name by listing two words with a space in between before defining the argument type.

func carpetCostHaving(..., carpetColor color: String = "tan") -> ...
//                         ↑           ↑__ local name
//                         |__ external name

You begin by defining your external argument name, followed by a space and then a local name. Within the function you use the local name anytime you reference that argument, that's why you're using just color within the function.

This allows you to be a little more flexible with the naming conventions within the scope of the function. If your function is specifically about carpets then it doesn't need you to prefix every variable with carpet, it's contextually implicit that color can only be about carpet color.

Outside of the function, color isn't very descriptive in the wider context where any number of things could all have colors (paint, floor tiles, etc.) so we're being more explicit about the name we use to pass carpet color into the function.

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Sahan Balasuriya

Sahan Balasuriya

why is it return(price, color) instead of return (price, carpetColor) I don't understand

1 Answer

Chris White

Chris White