Nil-coalescing Operator in Swift

main.swift

//
// UPDATE: This gist was rendered obsolete as of
// Xcode 6 Beta 5, which introduced the nil 
// coalescing operator in Swift proper (??).
//

/* Nil-coalescing operator */
infix operator !! {}
func !! <T> (
    value: T?,
    defaultValue: @auto_closure () -> T)
    -> T
{
    return value ? value! : defaultValue()
}


let text = "13"
let number = text.toInt() !! 0
println(number)
// prints: 13

println("word".toInt() !! 99 + 1)
// prints: 100


// Prints a message to show when it executes.
func getDefaultNumber() -> Int
{
    print("Getting the default number…")
    return -1
}

println("42".toInt() !! getDefaultNumber())
// prints: 42

println("Josh".toInt() !! getDefaultNumber())
// prints: Getting the default number…-1