swift - Why do I have to pass arguments to classes in key-value form? -

class namedshape {     var numberofsides: int = 0     var name: string      init(name: string) {         self.name = name     }      func simpledescription() -> string {         return "a shape \(numberofsides) sides named \(name)"     } } 

i have following example class. create new instance, do

let shape = namedshape(name: "test") 

the arguments captured init() function, right? however, if this:

let shape = namedshape("test") 

i missing argument label error!

however, if define silly function this:

func printint(numberin: int) {     println(numberin) } 

i can invoke fine using:

printint(5) 

however, if attempt invoke arguments formatted in way create class:

printint(numberin: 5) 

i extraneous argument label error!

help swift noob understand. why need label class arguments, can't label function arguments? why functions , classes different way? i'm sure there's i'm missing.

because initializer functions aren’t called function name, parameter types , names used disambiguate among multiple init() functions. thus, init() function parameters have external names default.

you can explicitly opt out of default parameter names underscore:

init(_ name: string) {     self.name = name }