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![MacWire
import com.softwaremill.macwire.MacwireMacros._!
object PresentWrapper extends App {!
!
!
lazy val ribbonSelector =
! ! ! wire[RibbonSelector]!
!
!
lazy val wrappingPaperFeeder =
! ! ! wire[WrappingPaperFeeder]!
!
!
lazy val presentPackager =
! ! ! wire[PresentPackager]
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-17-2048.jpg)
![Side-note: Scala Macros
❖
E.g. debug macro!
def debug(params: Any*) = macro debug_impl!
def debug_impl
! ! ! (c: Context)
! ! ! (params: c.Expr[Any]*): c.Expr[Unit]!
!
debug(presentCount) ⟹!
! println(“presentCount = “ + presentCount)
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-20-2048.jpg)
!
reify { println(
! paramRepExpr.splice +
! " = " +
! param.splice) }
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-21-2048.jpg)
![Side-note: Scala Macros
❖
MacWire!
def wire[T] = macro wire_impl[T]!
def wire_impl
! ! ! [T: c.WeakTypeTag]
! ! ! (c: Context): c.Expr[T]
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-22-2048.jpg)
![MacWire
import com.softwaremill.macwire.MacwireMacros._!
object PresentWrapper extends App {!
! lazy val ribbonSelector =
! ! ! ! wire[RibbonSelector]!
! lazy val wrappingPaperFeeder =
! ! ! ! wire[WrappingPaperFeeder]!
! lazy val presentPackager =
! ! ! ! wire[PresentPackager]
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-23-2048.jpg)
![Singleton & dependent
object NorthPole extends App {!
! // Singleton!
lazy val santaClaus = wire[SantaClaus]!
!
! // Dependent!
def gnome = wire[Gnome]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-25-2048.jpg)
![Modules
trait PresentWrapper {!
! lazy val ribbonSelector =
! ! ! ! wire[RibbonSelector]!
! lazy val wrappingPaperFeeder =
! ! ! ! wire[WrappingPaperFeeder]!
lazy val presentPackager =
! ! ! ! wire[PresentPackager]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-31-2048.jpg)
![Modules
trait PresentFactory extends PresentWrapper {!
! lazy val teddyBearProvider =
! ! ! ! wire[TeddyBearProvider]!
! lazy val toyTrainProvider =
! ! ! ! wire[ToyTrainProvider]!
lazy val presentAssembly =
! ! ! ! wire[PresentAssembly]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-32-2048.jpg)
![Modules
trait HomeOfSanta {!
! lazy val santaClaus = wire[SantaClaus]!
! lazy val rudolf = wire[Rudolf]!
! lazy val fireplace = wire[Fireplace]!
!
def presentAssembly: PresentAssembly!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-33-2048.jpg)
![Other features
❖
Interceptors!
!
trait Chimney {!
! lazy val presentTransferer =
! ! transactional(wire[PresentTransferer])!
! def transactional: Interceptor!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-38-2048.jpg)
![Other features
❖
Factories!
❖
a dedicated object or …!
!
trait PresentBoxer {!
! def box(size: Size) = wire[Box]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-39-2048.jpg)
![MacWire
import com.softwaremill.macwire.MacwireMacros._!
object PresentWrapper extends App {!
!
!
lazy val ribbonSelector =
! ! ! wire[RibbonSelector]!
!
!
lazy val wrappingPaperFeeder =
! ! ! wire[WrappingPaperFeeder]!
!
!
lazy val presentPackager =
! ! ! wire[PresentPackager]
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-17-2048.jpg)
![Side-note: Scala Macros
❖
E.g. debug macro!
def debug(params: Any*) = macro debug_impl!
def debug_impl
! ! ! (c: Context)
! ! ! (params: c.Expr[Any]*): c.Expr[Unit]!
!
debug(presentCount) ⟹!
! println(“presentCount = “ + presentCount)
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-20-2048.jpg)
!
reify { println(
! paramRepExpr.splice +
! " = " +
! param.splice) }
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-21-2048.jpg)
![Side-note: Scala Macros
❖
MacWire!
def wire[T] = macro wire_impl[T]!
def wire_impl
! ! ! [T: c.WeakTypeTag]
! ! ! (c: Context): c.Expr[T]
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-22-2048.jpg)
![MacWire
import com.softwaremill.macwire.MacwireMacros._!
object PresentWrapper extends App {!
! lazy val ribbonSelector =
! ! ! ! wire[RibbonSelector]!
! lazy val wrappingPaperFeeder =
! ! ! ! wire[WrappingPaperFeeder]!
! lazy val presentPackager =
! ! ! ! wire[PresentPackager]
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-23-2048.jpg)
![Singleton & dependent
object NorthPole extends App {!
! // Singleton!
lazy val santaClaus = wire[SantaClaus]!
!
! // Dependent!
def gnome = wire[Gnome]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-25-2048.jpg)
![Modules
trait PresentWrapper {!
! lazy val ribbonSelector =
! ! ! ! wire[RibbonSelector]!
! lazy val wrappingPaperFeeder =
! ! ! ! wire[WrappingPaperFeeder]!
lazy val presentPackager =
! ! ! ! wire[PresentPackager]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-31-2048.jpg)
![Modules
trait PresentFactory extends PresentWrapper {!
! lazy val teddyBearProvider =
! ! ! ! wire[TeddyBearProvider]!
! lazy val toyTrainProvider =
! ! ! ! wire[ToyTrainProvider]!
lazy val presentAssembly =
! ! ! ! wire[PresentAssembly]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-32-2048.jpg)
![Modules
trait HomeOfSanta {!
! lazy val santaClaus = wire[SantaClaus]!
! lazy val rudolf = wire[Rudolf]!
! lazy val fireplace = wire[Fireplace]!
!
def presentAssembly: PresentAssembly!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-33-2048.jpg)
![Other features
❖
Interceptors!
!
trait Chimney {!
! lazy val presentTransferer =
! ! transactional(wire[PresentTransferer])!
! def transactional: Interceptor!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-38-2048.jpg)
![Other features
❖
Factories!
❖
a dedicated object or …!
!
trait PresentBoxer {!
! def box(size: Size) = wire[Box]!
}
11/12/2013 BuildStuff 2013
@adamwarski](https://crownmelresort.com/image.slidesharecdn.com/scaladi-131211045353-phpapp01/75/The-no-framework-Scala-Dependency-Injection-Framework-39-2048.jpg)
Uploaded byAdam Warski
The no-framework Scala Dependency Injection Framework
The document discusses a no-framework dependency injection approach in Scala, emphasizing that dependency injection can be achieved using the host language without the complexity of external frameworks. It presents various methods of implementing manual and macro-based dependency injection while highlighting the importance of modules, scopes, and testing in this context. The author advocates for using native Scala features to provide flexibility and reduce constraints associated with traditional dependency injection frameworks.
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The no-framework Scala Dependency Injection Framework
- 1. The no-framework Scala DependencyInjection framework 11/12/2013 BuildStuff 2013 Adam Warski @adamwarski BuildStuff 2013
- 2. You don’t needanything special to do Dependency Injection 11/12/2013 BuildStuff 2013 @adamwarski
- 3. We often over-complicate 11/12/2013BuildStuff 2013 @adamwarski
- 4. Who Am I? ❖ Day:coding @ SoftwareMill! ❖ Afternoon: playgrounds, Duplos, etc.! ❖ Evenings: blogging, open-source! ❖ Original author of Hibernate Envers! ❖ ElasticMQ, Veripacks, MacWire! ❖ http://www.warski.org 11/12/2013 BuildStuff 2013 @adamwarski
- 5. What is Dependency Injection? 11/12/2013BuildStuff 2013 @adamwarski
- 6. What is DI? classPresentPackager {! ! def wrap() {! ! ! new RibbonSelector().selectRandom()! ! ! …! } ! } 11/12/2013 BuildStuff 2013 @adamwarski
- 7. What is DI? classPresentPackager(rs: RibbonSelector) {! ! def wrap() {! ! ! rs.selectRandom()! ! ! …! } ! } 11/12/2013 BuildStuff 2013 @adamwarski
- 8. Yes, DI isjust using parameters 11/12/2013 BuildStuff 2013 @adamwarski
- 9. Why? ❖ Restrict the knowledgeof the class class PresentPackager { class PresentPackager ! (rs: RibbonSelector) { ! ! ! ! ! } def wrap() { ! new RibbonSelector() ! ! .selectRandom() ! … } 11/12/2013 BuildStuff 2013 ! ! ! ! } def wrap() { ! rs.selectRandom() ! … } @adamwarski
- 10. But still … ❖ Weneed to have the news somewhere 11/12/2013 BuildStuff 2013 @adamwarski
- 11. Let’s create aDI container! a.k.a. framework 11/12/2013 BuildStuff 2013 @adamwarski
- 12. DI in Java ❖ Manyframeworks! ❖ Configuration via:! ❖ XML! ❖ annotations! ❖ Java 11/12/2013 BuildStuff 2013 @adamwarski
- 13. What’s wrong withthat? ❖ Do I really need a DI framework? 11/12/2013 BuildStuff 2013 @adamwarski
- 14. Let’s go back… ❖ … and just use our host language! ❖ in this case, Scala! ❖ mapping DI framework concepts to native language constructs 11/12/2013 BuildStuff 2013 @adamwarski
- 15. Manual DI! ! object PresentWrapperextends App {! ! ! val ribbonSelector = ! ! ! new RibbonSelector()! ! ! val wrappingPaperFeeder = ! ! ! new WrappingPaperFeeder()! ! ! ! ! val presentPackager = ! ! ! new PresentPackager( ! ! ! ! ribbonSelector, ! ! ! ! wrappingPaperFeeder)! } 11/12/2013 BuildStuff 2013 @adamwarski
- 16. Manual DI! ! object PresentWrapperextends App {! ! ! lazy val ribbonSelector = ! ! ! new RibbonSelector()! ! ! lazy val wrappingPaperFeeder = ! ! ! new WrappingPaperFeeder()! ! ! ! ! lazy ! ! ! ! ! ! val presentPackager = ! new PresentPackager( ! ! ribbonSelector, ! ! wrappingPaperFeeder)! } 11/12/2013 BuildStuff 2013 @adamwarski
- 17. MacWire import com.softwaremill.macwire.MacwireMacros._! object PresentWrapperextends App {! ! ! lazy val ribbonSelector = ! ! ! wire[RibbonSelector]! ! ! lazy val wrappingPaperFeeder = ! ! ! wire[WrappingPaperFeeder]! ! ! lazy val presentPackager = ! ! ! wire[PresentPackager] } 11/12/2013 BuildStuff 2013 @adamwarski
- 18. Side-note: Scala Macros 11/12/2013BuildStuff 2013 @adamwarski
- 19. Side-note: Scala Macros ❖ Scalacode executed at compile time! ❖ Operate on trees! ❖ Can inspect the environment, generate code! ❖ the code is type-checked 11/12/2013 BuildStuff 2013 @adamwarski
- 20. Side-note: Scala Macros ❖ E.g.debug macro! def debug(params: Any*) = macro debug_impl! def debug_impl ! ! ! (c: Context) ! ! ! (params: c.Expr[Any]*): c.Expr[Unit]! ! debug(presentCount) ⟹! ! println(“presentCount = “ + presentCount) 11/12/2013 BuildStuff 2013 @adamwarski
- 21. Side-note: Scala Macros ❖ Debugmacro implementation! import c.universe._! val paramRep = show(param.tree) val paramRepTree = Literal(Constant(paramRep)) val paramRepExpr = c.Expr[String](paramRepTree)! reify { println( ! paramRepExpr.splice + ! " = " + ! param.splice) } 11/12/2013 BuildStuff 2013 @adamwarski
- 22. Side-note: Scala Macros ❖ MacWire! defwire[T] = macro wire_impl[T]! def wire_impl ! ! ! [T: c.WeakTypeTag] ! ! ! (c: Context): c.Expr[T] 11/12/2013 BuildStuff 2013 @adamwarski
- 23. MacWire import com.softwaremill.macwire.MacwireMacros._! object PresentWrapperextends App {! ! lazy val ribbonSelector = ! ! ! ! wire[RibbonSelector]! ! lazy val wrappingPaperFeeder = ! ! ! ! wire[WrappingPaperFeeder]! ! lazy val presentPackager = ! ! ! ! wire[PresentPackager] } 11/12/2013 BuildStuff 2013 @adamwarski
- 24. Scopes ❖ How long willan object (instance) live? 11/12/2013 BuildStuff 2013 @adamwarski
- 25. Singleton & dependent objectNorthPole extends App {! ! // Singleton! lazy val santaClaus = wire[SantaClaus]! ! ! // Dependent! def gnome = wire[Gnome]! } 11/12/2013 BuildStuff 2013 @adamwarski
- 26. Arbitrary scopes trait WebFrontEnd{ ! lazy val loggedInUser = ! ! session(new LoggedInUser) ! def session: Scope }! ! trait Scope { ! def apply(factory: => T): T } 11/12/2013 BuildStuff 2013 @adamwarski
- 27. Arbitrary scopes object MyAppextends WebFrontEnd { ! val session: Scope = ! ! ! ! new ThreadLocalScope()! ! val filter = new ScopeFilter(session) ! // bootstrap the web server ! // using the filter } 11/12/2013 BuildStuff 2013 @adamwarski
- 28. Arbitrary scopes class ScopeFilter(sessionScope:ThreadLocalScope) ! ! ! extends Filter {! ! def doFilter(request: ServletRequest) { ! ! sessionScope ! ! ! .withStorage(request.getSession()) {! ! ! ! request.proceed()! ! ! } ! } } 11/12/2013 BuildStuff 2013 @adamwarski
- 29. Modules ❖ Pre-wired! ❖ Composable! ❖ Dependencies! ❖ Module per package?! ❖ Veripacks:) 11/12/2013 BuildStuff 2013 @adamwarski
- 30. Modules ❖ Module: trait! ❖ Pre-wired: new,MacWire! ❖ Composable: extends/with! ❖ Dependencies: extends/with / abstract members 11/12/2013 BuildStuff 2013 @adamwarski
- 31. Modules trait PresentWrapper {! !lazy val ribbonSelector = ! ! ! ! wire[RibbonSelector]! ! lazy val wrappingPaperFeeder = ! ! ! ! wire[WrappingPaperFeeder]! lazy val presentPackager = ! ! ! ! wire[PresentPackager]! } 11/12/2013 BuildStuff 2013 @adamwarski
- 32. Modules trait PresentFactory extendsPresentWrapper {! ! lazy val teddyBearProvider = ! ! ! ! wire[TeddyBearProvider]! ! lazy val toyTrainProvider = ! ! ! ! wire[ToyTrainProvider]! lazy val presentAssembly = ! ! ! ! wire[PresentAssembly]! } 11/12/2013 BuildStuff 2013 @adamwarski
- 33. Modules trait HomeOfSanta {! !lazy val santaClaus = wire[SantaClaus]! ! lazy val rudolf = wire[Rudolf]! ! lazy val fireplace = wire[Fireplace]! ! def presentAssembly: PresentAssembly! } 11/12/2013 BuildStuff 2013 @adamwarski
- 34. Modules trait PresentWrapper {… } trait PresentFactory extends PresentWrapper { } trait HomeOfSanta { … }! ! object NorthPole ! extends PresentWrapper ! with PresentFactory ! with HomeOfSanta {! ! santaClaus.deliver()! } 11/12/2013 BuildStuff 2013 @adamwarski
- 35. Testing Santa’s Home classHomeOfSantaTest extends FlatSpec {! ! it should “deliver presents” in {! ! ! val mockPresentAssembly = …! ! ! new HomeOfSanta {! !! lazy val presentAssembly = ! ! ! ! mockPresentAssembly }! ! ! …! ! }! } 11/12/2013 BuildStuff 2013 @adamwarski
- 36. Cake Pattern trait PresentPackagerModule{! ! ! ! ! ! ! class PresentPackager { ! def wrap() { ! ! ribbonSelector.selectRandom() ! ! … ! } } ! lazy val presentPackager = new PresentPackager() ! def ribbonSelector: RibbonSelector } 11/12/2013 BuildStuff 2013 @adamwarski
- 37. Cake Pattern val cake= new PresentPackagerModule ! with RibbonSelectorModule ! with WrappingPaperFeederModule ! with TeddyBearProviderModule ! with ToyTrainProviderModule ! with PresentAssemblyModule ! with … { } 11/12/2013 BuildStuff 2013 @adamwarski
- 38. Other features ❖ Interceptors! ! trait Chimney{! ! lazy val presentTransferer = ! ! transactional(wire[PresentTransferer])! ! def transactional: Interceptor! } 11/12/2013 BuildStuff 2013 @adamwarski
- 39. Other features ❖ Factories! ❖ a dedicatedobject or …! ! trait PresentBoxer {! ! def box(size: Size) = wire[Box]! } 11/12/2013 BuildStuff 2013 @adamwarski
- 40. Other features ❖ Instance maps! ❖ forintegrating e.g. with Play! ❖ Factories! ❖ In-method wiring! ❖ More coming, someday :) 11/12/2013 BuildStuff 2013 @adamwarski
- 41. Summing up ❖ Reconsider usinga framework! ❖ Native Scala gives a lot of power! ❖ ❖ ❖ use it! wisely! More flexibility (less constraints) 11/12/2013 BuildStuff 2013 @adamwarski
- 42.
- 43.