Optional Loggin extension

OptionalExtension.swift

import Foundation


//
// MARK:- Private
//
class MyAwesomeLogger {
    static func log(message: String) {
        print(message)
    }
}

struct Friend {}
class DB {
    static func friend(byName name: String) -> Friend? {
        return nil
    }
}

//
//  MARK: Fun things
//

extension Optional {
    func logNil<T>(function: String = #function,
                filename: String = #file,
                line: Int = #line,
                message: String = "not found",
                context: T
        ) -> Wrapped? {
        if self == nil {
            let messageToLog = "\((filename as NSString).lastPathComponent):\(line) \(function) \(context) \(message)"
            MyAwesomeLogger.log(message: messageToLog)
        }
        return self
    }
}


func findFriend(byName name: String) -> Friend? {
    return DB.friend(byName: name)
        .logNil(context: name)  // <-- Here is the trick
}

findFriend(byName: "Awesome")

// Output
// playground50.swift:40 findFriend(byName:) Awesome not found