Swift - Serious functions: Anonymous Functions, Scope and Closures(nested function, environment))

The Swift Programming Language
Apple Inc.

開発環境

• OS X Mavericks - Apple(OS)
• Xcode 6.1 Beta
• Swift (プログラミング言語)

Head First JavaScript Programming (Eric T. Freeman (著)、 Elisabeth Robson (著)、 O'Reilly Media )のChapter 11(Serious functions: Anonymous Functions, Scope and Closures)、EXERCISE(p.500)をSwiftで考えてみる。

EXERCISE(p.500)

コード(Xcode)

main.swift

//
//  main.swift
//  sample500
//
//  Created by kamimura on 9/21/14.
//  Copyright (c) 2014 kamimura. All rights reserved.
//

import Foundation

func makePassword(password:String) -> String -> Bool {
    return {(password_guess:String) in password_guess == password}
}

func mult(n:Int) -> Int -> Int {
    return {(result:Int) in result * n}
}

struct S {
    let increment:() -> Int
}
func makeCounter() -> S {
    var count:Int = 0
    return S(increment: {() in
        count += 1
        return count
    })
}

let p1 = makePassword("pass1")
let p2 = makePassword("pass2")
let mult5 = mult(5)
let mult10 = mult(10)
let c1 = makeCounter()
let c2 = makeCounter()

println(p1("pass1"))
println(p1("pass2"))
println(p2("pass1"))
println(p2("pass2"))

println(mult5(15))
println(mult5(20))
println(mult10(15))
println(mult10(20))

println(c1.increment())
println(c1.increment())
println(c2.increment())
println(c2.increment())

入出力結果(Console Output)

true
false
false
true
75
100
150
200
1
2
1
2
Program ended with exit code: 0