Example of using the ThrowingProviders and CheckedProviders in Guice. See full context: http://www.ethanjoachimeldridge.info/tech-blog/guice-scala-checked-providers

GuiceThrowingProvidersExample.scala

import com.google.inject.{AbstractModule, Provides, Guice}
import com.google.inject.throwingproviders.{ CheckedProvides, CheckedProvider, ThrowingProviderBinder }
import com.typesafe.config.{ ConfigException, ConfigFactory } 

import java.net.{URL, MalformedURLException}
import javax.inject.Inject

import scala.collection.JavaConversions._
import scala.util.{Try, Success, Failure}

object Example extends App {

	case class DataSourceParams(val url: URL, @transient val accessCode: String)

	case class RemotePizzaOrder(
		val numberOfPizzas: Long,
		val pizzaToppings: Seq[String],
		val dietRestrictions: Seq[String]
	)

	class UnsafePizzaModule extends AbstractModule {

		def configure {}

		@Provides
		def provideDataSourceParams() = {
			val conf = ConfigFactory.load() // Might throw an exception!
			val url = new URL(conf.getString("dsp.url")) // Might throw an exception!
			val accessCode = conf.getString("dsp.accessCode") // Might throw an expcetion!
			DataSourceParams(url, accessCode)
		}

		@Provides
		def provideRemotePizzaOrder(dataSourceParams: DataSourceParams) = {
			val conf = ConfigFactory.parseURL(dataSourceParams.url) // Might throw an exception
			RemotePizzaOrder(
				conf.getLong("rpo.numberOfPizzas"),
				conf.getStringList("rpo.pizzaToppings"),
				conf.getStringList("rpo.dietRestrictions")
			) // Any of the conf.get* might throw an exception
		}
	}

	class PizzaHandler @Inject() (order: RemotePizzaOrder) {
		println(order)
	}

	// Uncomment these to get explosions
	//val injector = Guice.createInjector(new UnsafePizzaModule)
	//val unsafeHandler = injector.getInstance(classOf[PizzaHandler])
	//println(unsafeHandler) // You won't get here because of exceptions	

	trait DataSourceProviderLike extends CheckedProvider[DataSourceParams] {
		@throws(classOf[ConfigException])
		@throws(classOf[MalformedURLException])
		def get(): DataSourceParams
	}

	class DataSourceProvider extends DataSourceProviderLike {
		@throws(classOf[ConfigException])
		@throws(classOf[MalformedURLException])
		def get() = {
			val conf = ConfigFactory.load() // Might throw an exception!
			val url = new URL(conf.getString("dsp.url")) // Might throw an exception!
			val accessCode = conf.getString("dsp.accessCode") // Might throw an expcetion!
			DataSourceParams(url, accessCode)
		}
	}

	trait RemotePizzaOrderProviderLike extends CheckedProvider[RemotePizzaOrder] {
		@throws(classOf[ConfigException])
		def get(): RemotePizzaOrder
	}

	class RemotePizzaOrderProvider @Inject() (dataSourceParamsProvider: DataSourceProviderLike) extends RemotePizzaOrderProviderLike {
		@throws(classOf[ConfigException])
		def get() = {
			Try(dataSourceParamsProvider.get()) match {
				case Success(dataSourceParams) => {
					val conf = ConfigFactory.parseURL(dataSourceParams.url) 
					RemotePizzaOrder(
						conf.getLong("rpo.numberOfPizzas"),
						conf.getStringList("rpo.pizzaToppings"),
						conf.getStringList("rpo.dietRestrictions")
					) 
				}
				case Failure(exception) => {
					println("Can't get pizza order right now, try again later...")
					RemotePizzaOrder(0, Nil, Nil)
				}
			}
		}
	}
	
	class SaferPizzaModuleBound extends AbstractModule {
		def configure() {
			ThrowingProviderBinder.create(binder())
				.bind(classOf[DataSourceProviderLike], classOf[DataSourceParams])
				.to(classOf[DataSourceProvider])

			ThrowingProviderBinder.create(binder())
				.bind(classOf[RemotePizzaOrderProviderLike], classOf[RemotePizzaOrder])
				.to(classOf[RemotePizzaOrderProvider])
		}
	}

	class SaferPizzaModuleInstalled extends AbstractModule {
		def configure() {
			install(ThrowingProviderBinder.forModule(this))
		}

		@CheckedProvides(classOf[DataSourceProviderLike])
		def provideDataSourceParams() = {
			val conf = ConfigFactory.load() 
			val url = new URL(conf.getString("dsp.url"))
			val accessCode = conf.getString("dsp.accessCode")
			DataSourceParams(url, accessCode)
		}

		@CheckedProvides(classOf[RemotePizzaOrderProviderLike])
		def provideRemotePizzaOrder(dataSourceParamsProvider: DataSourceProviderLike) = {
			Try(dataSourceParamsProvider.get()) match {
				case Success(dataSourceParams) => {
					val conf = ConfigFactory.parseURL(dataSourceParams.url)
					RemotePizzaOrder(
						conf.getLong("rpo.numberOfPizzas"),
						conf.getStringList("rpo.pizzaToppings"),
						conf.getStringList("rpo.dietRestrictions")
					) 
				}
				case Failure(exception) => {
					println("Can't get pizza order right now, try again later...")
					RemotePizzaOrder(0, Nil, Nil)
				}
			}
		}
	}

	class SaferPizzaHandler @Inject() (order: RemotePizzaOrderProviderLike) {
		println(order.get())
	}

	val injector = Guice.createInjector(new SaferPizzaModuleBound)
	val saferHandler = injector.getInstance(classOf[SaferPizzaHandler])

	val injector2 = Guice.createInjector(new SaferPizzaModuleInstalled)
	val saferHandler2 = injector2.getInstance(classOf[SaferPizzaHandler])

}