interface Factory<out T> {
       fun create(): T
    }
    typealias PrinterFun = (String) -> Unit
    interface PrinterFactory : Factory<PrinterFun>
    interface MessageFactory : Factory<String>
    interface MessagePrinter {
       fun print(pf: PrinterFactory, mf: MessageFactory)
    }
    class PrinterFactoryImpl : PrinterFactory {
       override fun create(): PrinterFun = ::print
    }
    class MessageFactoryImpl : MessageFactory {
   companion object {
       const val DEFAULT_MESSAGE = "Hello World"
   }
   override fun create(): String = DEFAULT_MESSAGE
   class MessagePrinterImpl : MessagePrinter {
       override fun print(pf: PrinterFactory, mf: MessageFactory) {
           pf.create().invoke(mf.create())
       }
   }
   class ImplProvider {
       private val impls = HashMap<KClass<out Any>, Any>()
       fun <T : Any> setImpl(clazz: KClass<T>, t: T) {
           impls[clazz] = t
       }
       fun <T : Any> getImpl(clazz: KClass<T>): T {
           return (impls[clazz] as? T) ?: throw Exception("No impl")
       }
   }
   fun main(args: Array<String>) {
       val implProvider = ImplProvider()
       implProvider.setImpl(PrinterFactory::class, PrinterFactoryImpl())
       implProvider.setImpl(MessageFactory::class, MessageFactoryImpl())
       implProvider.setImpl(MessagePrinter::class, MessagePrinterImpl())
       implProvider.getImpl(MessagePrinter::class)
               .print(implProvider.getImpl(PrinterFactory::class),
                       implProvider.getImpl(MessageFactory::class))
   }

class TimeFormatter {
       private val timeFormat = SimpleDateFormat("HH:mm:ss", Locale.getDefault())
       fun formatTime() = timeFormat.format(Date())
    }

open class UiComponent() {
   var mode : Int = 0
   fun showTextAndImage(text:String, image: Image){
       mode = 0
       ...
   }
   fun showButton(text:String, action: Runnable){
       mode = 1
       ...
   }
   ...
}

class MyUiComponent(): UiComponent(){
   fun doMagic(){mode = 3}
}

class DownloadManager() {
   fun download(downloadable: Downloadable) {
       val stream = downloadable.openStream()
       val file = File(downloadable.getFileName())
       //логика записи в файл
   }
}
interface Downloadable {
   fun openStream(): InputStream
   fun getFileName(): String
}
class SimpleDownloadableFile(val name: String,
                             val url: String) : Downloadable {
   override fun openStream() = URL(url).openStream()
   override fun getFileName() = name
}
class HeaderFile(val name: String,
                 val url: String,
                 val headers: Map<String, String>) : Downloadable {
   override fun openStream(): InputStream {
            /*формирование запроса и получении потока*/
   }
   override fun getFileName() = name
}

interface Something
interface SomethingSpecific : Something
interface WritableSomething : SomethingSpecific {
   fun writeToFile()
}
interface GetableWritable<T> : WritableSomething {
   fun obtain(): T
}
abstract class ObtainableFile(val name: String) : GetableWritable<File> {
   override fun obtain() = File(name)
   override fun writeToFile() = obtain().write(getStream())
   abstract fun getStream(): InputStream
}
class UrlFile(url: String, name: String) : ObtainableFile(name) {
   override fun getStream(): InputStream = URL(url).openStream()
}

open class ServerManager {
   open fun getData(): String = "запрос на сервер"
}
open class CacheManager {
   open fun saveData(data: String) {/*сохранение в файл/базу данных */}
}
class DataManager{
   fun getDataAndCache(){
       val data = ServerManager().getData()
       CacheManager().saveData(data)
   }
}

class DataManager(private val serverManager: ServerManager,
                  private val cacheManager: CacheManager) {
   fun getDataAndCache() {
       val data = serverManager.getData()
       cacheManager.saveData(data)
   }
}

interface ServerManager {
   fun getData(): String
}
open class ServerManagerImpl : ServerManager {
   override fun getData(): String = "запрос на сервер"
}
interface CacheManager {
   fun saveData(data: String)
}
open class CacheManagerImpl : CacheManager {
   override fun saveData(data: String) {
       /*сохранение в файл/базу данных */
   }
}
interface DataManager {
   fun getDataAndCache()
}
class DataManagerImpl(
       private val serverManager: ServerManager,
       private val cacheManager: CacheManager,
) : DataManager {
   override fun getDataAndCache() {
       val data = serverManager.getData()
       cacheManager.saveData(data)
   }
}
fun foo(){
   val dataManager: DataManager = DataManagerImpl(
           ServerManagerImpl(),
           CacheManagerImpl()
   )
   dataManager.getDataAndCache()
}

interface TextProvider {
   fun getText(): String
}
class SimpleTextProvider(private val text: String) : TextProvider {
   override fun getText(): String = text
}
class Printer(private val textProvider: TextProvider) {
   fun printText() {
       println(textProvider.getText())
   }
}
fun main() {
   Printer(SimpleTextProvider("text")).printText()
}