error.swift

import Foundation

// See: https://developer.apple.com/swift/blog/?id=15

struct Error: ErrorType {
    var _domain: String {return "com.sadun"}
    var _code: Int {return 0}
}

enum MyError : ErrorType {
    case Error(reason: String, source: String)
    
    // Thanks Mike Ash!
    static func Build(
        reason: String, source: String = __FUNCTION__, file: String = __FILE__, line: Int = __LINE__) -> MyError {
        return MyError.Error(reason:reason, source:"Thrown in \(source) (File: \(file) Line: \(line))")
    }
}

func test() throws -> Int {
    let value = arc4random_uniform(2)
    if value > 0 {
        return numericCast(arc4random_uniform(20))
    } else {
        throw MyError.Build("Tough luck")
    }
}

do { try test() }catch{ print(error) }