error.swift

//http://swift.gg/2015/11/27/implementing-printing-versions-of-try-and-try-on-steroids-in-swiftlang/
import Foundation

// Generic Error
public struct Error: ErrorType {let reason: String}

/**
 Printing version of try? Call either with standard or autoclosure approach
 ```
 let contents = attempt{try NSFileManager.defaultManager().contentsOfDirectoryAtPath(fakePath)}
 let contents = attempt{try NSFileManager.defaultManager().contentsOfDirectoryAtPath(XCPlaygroundSharedDataDirectoryURL.path!)}
 ```
 
 - Returns: Optional that is nil when the called closure throws
 */

public func attempt<T>(source source: String = __FUNCTION__, file: String = __FILE__, line: Int = __LINE__, closure: () throws -> T) -> Optional<T>{
    do {
        return try closure()
    } catch {
        let fileName = (file as NSString).lastPathComponent
        let report = "Error \(fileName):\(source):\(line):\n    \(error)"
        print(report)
        return nil
    }
}

/**
 A printing alternative to try? that returns Boolean value
 
 ```
 let success = attemptFailable{try "Test".writeToFile(fakePath, atomically: true, encoding: NSUTF8StringEncoding)}
 ```
 
 - Returns: Boolean value, false if the called closure throws an error, true otherwise
 */
public func attemptFailable(source source: String = __FUNCTION__, file: String = __FILE__, line: Int = __LINE__, closure: () throws -> Void) -> Bool {
    do {
        try closure()
        return true
    } catch {
        let fileName = (file as NSString).lastPathComponent
        let report = "Error \(fileName):\(source):\(line):\n    \(error)"
        print(report)
        return false
    }
}

/**
 Slightly more informative version of try!. When shouldCrash is set to false,
 execution will continue without a fatal error even if an error is thrown
 
 ```
 doOrDie(shouldCrash: false, closure: {try "Test".writeToFile(fakePath, atomically: true, encoding: NSUTF8StringEncoding)})
 // or
 doOrDie(shouldCrash:false){try NSFileManager.defaultManager().removeItemAtURL(fakeURL)}
 // or
 doOrDie{try "Test".writeToFile(fakePath, atomically: true, encoding: NSUTF8StringEncoding)}
 ```
 */
public func doOrDie(source: String = __FUNCTION__,
    file: String = __FILE__, line: Int = __LINE__, shouldCrash: Bool = true, closure: () throws -> Void) {
        let success = attemptFailable(source: source, file: file, line: line, closure: closure)
        if shouldCrash && !success {fatalError("Goodbye cruel world")}
}