Effective Reactive Architecture

Video: https://youtu.be/7fE5MDQ_Sc4

Your relationship with RxJava doesn't have to be complicated. You may have found many ways to use it wrong but it is powerful when used properly.In fact, RxJava can guide you in shaping a sound architecture for your app. To do this, you only have to follow a few but decisive principles.

In this talk, you'll:
- Explore how side-effect isolation can help avoiding bugs.
- Learn how to model your data and share it as one unique stream between your view and your presenter.
- Discover the ways a unidirectional data flow makes adding new functionality easy and safe.
- Look at how you can easily deal with collateral side effects, such as navigation.

After this talk, you’ll be able to write a robust and reactive architecture for your app, taking full advantage of RxJava.

Transcript

1. Benoît Quenaudon @oldergod
   Effective Reactive Architecture
   

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2. View Slide

3. Side-Effects Isolation
   

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4. class ProfileView {
   val navigator: Navigator
   val nameView: TextView
   val appService: AppService
   val nameSubject = BehaviorSubject.create()
   fun onStart() {
   }
   }
   

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5. class ProfileView {
   val navigator: Navigator
   val nameView: TextView
   val appService: AppService
   val nameSubject = BehaviorSubject.create()
   fun onStart() {
   nameSubject
   .switchMap { name ->
   appService.profile()
   .map { profile -> profile.prefix }
   .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
   }
   .subscribe(nameView::setText)
   }
   }
   

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6. class ProfileView {
   val navigator: Navigator
   val nameView: TextView
   val appService: AppService
   val nameSubject = BehaviorSubject.create()
   fun onStart() {
   nameSubject
   .switchMap { name ->
   appService.profile()
   .map { profile -> profile.prefix }
   .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
   }
   .subscribe(nameView::setText)
   // hint grows the view in width so hide it if unnecessary
   nameSubject
   .map { name -> if (name.isEmpty()) "Set your name" else "" }
   .subscribe(nameView::setHint)
   }
   }
   

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7. class ProfileView {
   val navigator: Navigator
   val nameView: TextView
   val appService: AppService
   val nameSubject = BehaviorSubject.create()
   fun onStart() {
   nameSubject
   .switchMap { name ->
   appService.profile()
   .map { profile -> profile.prefix }
   .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
   }
   .subscribe(nameView::setText)
   // hint grows the view in width so hide it if unnecessary
   nameSubject
   .map { name -> if (name.isEmpty()) "Set your name" else "" }
   .subscribe(nameView::setHint)
   appService.profile().subscribe(this::populateProfile)
   }
   }
   

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8. class ProfileView {
   val navigator: Navigator
   val nameView: TextView
   val appService: AppService
   val nameSubject = BehaviorSubject.create()
   fun onStart() {
   nameSubject
   .switchMap { name ->
   appService.profile()
   .map { profile -> profile.prefix }
   .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
   }
   .subscribe(nameView::setText)
   // hint grows the view in width so hide it if unnecessary
   nameSubject
   .map { name -> if (name.isEmpty()) "Set your name" else "" }
   .subscribe(nameView::setHint)
   appService.profile().subscribe(this::populateProfile)
   }
   fun populateProfile(profile: Profile) {
   nameSubject.onNext(profile.name)
   // rendering other stuff
   }
   }
   

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9. class ProfileView {
   val navigator: Navigator
   val nameView: TextView
   val appService: AppService
   val nameSubject = BehaviorSubject.create()
   fun onStart() {
   nameSubject
   .switchMap { name ->
   appService.profile()
   .map { profile -> profile.prefix }
   .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
   }
   .subscribe(nameView::setText)
   // hint grows the view in width so hide it if unnecessary
   nameSubject
   .map { name -> if (name.isEmpty()) "Set your name" else "" }
   .subscribe(nameView::setHint)
   appService.profile().subscribe(this::populateProfile)
   }
   fun populateProfile(profile: Profile) {
   nameSubject.onNext(profile.name)
   // rendering other stuff
   }
   fun onSetNameDialogResult(newName: String) = setName(newName)
   }
   

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10. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    }
    }
    

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11. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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12. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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13. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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14. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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15. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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16. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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17. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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18. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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19. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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20. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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21. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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22. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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23. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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24. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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25. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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26. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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27. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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28. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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29. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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30. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

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31. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

32. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

33. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

34. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

35. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

36. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

37. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

38. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

39. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

40. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

41. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

42. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

43. View Slide

44. How about Side Effects?
    

    View Slide

45. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

46. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

47. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

48. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

49. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

50. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

51. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

52. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

53. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

54. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

55. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

56. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

57. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

58. fun onStart() {
    nameSubject
    .switchMap { name ->
    appService.profile()
    .map { profile -> profile.prefix }
    .map { profile -> if (name.isEmpty()) "" else "$prefix $name" }
    }
    .subscribe(nameView::setText)
    // hint grows the view in width so hide it if unnecessary
    nameSubject
    .map { name -> if (name.isEmpty()) "Set your name" else "" }
    .subscribe(nameView::setHint)
    appService.profile().subscribe(this::populateProfile)
    }
    fun populateProfile(profile: Profile) {
    nameSubject.onNext(profile.name)
    // rendering other stuff
    }
    fun onSetNameDialogResult(newName: String) = setName(newName)
    fun setName(newName: String) {
    nameSubject.onNext(newName)
    appService.setName(newName)
    .subscribe { response ->
    when {
    response.isValid -> nameSubject.onNext(response.name)
    response.isInvalid -> navigator.goTo(response.error)
    }
    }
    }
    

    View Slide

59. class ProfileView {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    fun onStart() {
    }
    }
    

    View Slide

60. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    fun onStart() {
    }
    }
    

    View Slide

61. sealed class Event {
    data class EditName(val newName: String) : Event()
    }
    

    View Slide

62. sealed class Result {
    data class ProfileResult(val profile: Profile) : Result()
    data class NameValid(val name: String) : Result()
    object NameInvalid : Result()
    }
    

    View Slide

63. data class ViewModel(
    val stuff: Any?,
    val prefixedName: PrefixedName
    )
    

    View Slide

64. data class ViewModel(
    val stuff: Any?,
    val prefixedName: PrefixedName
    ) {
    data class PrefixedName(
    val prefix: String,
    val name: String
    ) {
    fun compute(name:String): String = if (name.isEmpty()) "" else "$prefix $name"
    }
    }
    

    View Slide

65. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    fun onStart() {
    }
    }
    

    View Slide

66. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    }
    }
    

    View Slide

67. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    .subscribe { viewModel ->
    }
    }
    }
    

    View Slide

68. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

69. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    }
    )
    }
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

70. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    }
    )
    }
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

71. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    

    View Slide

72. class ProfileViewRemix {
    val navigator: Navigator
    val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

73. val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

74. val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

75. val nameView: TextView
    val appService: AppService
    val nameSubject = BehaviorSubject.create()
    val events = PublishSubject.create()
    fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

76. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    }
    

    View Slide

77. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    

    View Slide

78. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

79. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

80. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

81. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

82. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

83. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

84. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

85. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

86. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

87. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

88. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

89. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

90. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

91. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

92. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

93. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

94. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

95. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

96. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

97. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

98. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

99. fun onStart() {
    events.publish { events ->
    Observable.merge(
    events.filterIsInstance()
    .switchMap { event ->
    appService.setName(event.newName).map { response ->
    when {
    response.isValid -> NameValid(response.name)
    response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
    }
    }
    .startWith(NameValid(event.newName))
    }
    )
    }
    .mergeWith(appService.profile().map(::ProfileResult))
    .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
    BiFunction { previous: ViewModel, result: Result ->
    when (result) {
    is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
    is NameInvalid -> previous
    is ProfileResult -> previous.copy(
    stuff = result.profile,
    prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
    )
    }
    })
    .subscribe { viewModel ->
    nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
    nameView.text = viewModel.prefixedName.compute()
    // rendering other stuff
    }
    }
    fun onSetNameDialogResult(newName: String) {
    events.onNext(EditName(newName))
    }
    

    View Slide

100. fun onStart() {
     events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     .subscribe { viewModel ->
     nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
     nameView.text = viewModel.prefixedName.compute()
     // rendering other stuff
     }
     }
     fun onSetNameDialogResult(newName: String) {
     events.onNext(EditName(newName))
     }
     

     View Slide

101. fun onStart() {
     events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     .subscribe { viewModel ->
     nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
     nameView.text = viewModel.prefixedName.compute()
     // rendering other stuff
     }
     }
     fun onSetNameDialogResult(newName: String) {
     events.onNext(EditName(newName))
     }
     

     View Slide

102. fun onStart() {
     events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     .subscribe { viewModel ->
     nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
     nameView.text = viewModel.prefixedName.compute()
     // rendering other stuff
     }
     }
     fun onSetNameDialogResult(newName: String) {
     events.onNext(EditName(newName))
     }
     

     View Slide

103. fun onStart() {
     events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     .subscribe { viewModel ->
     nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
     nameView.text = viewModel.prefixedName.compute()
     // rendering other stuff
     }
     }
     fun onSetNameDialogResult(newName: String) {
     events.onNext(EditName(newName))
     }
     

     View Slide

104. fun onStart() {
     events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     .subscribe { viewModel ->
     nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
     nameView.text = viewModel.prefixedName.compute()
     // rendering other stuff
     }
     }
     fun onSetNameDialogResult(newName: String) {
     events.onNext(EditName(newName))
     }
     

     View Slide

105. View Slide

106. One Stream
     Let's organize it
     

     View Slide

107. fun onStart() {
     events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     .subscribe { viewModel ->
     nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
     nameView.text = viewModel.prefixedName.compute()
     // rendering other stuff
     }
     }
     fun onSetNameDialogResult(newName: String) {
     events.onNext(EditName(newName))
     }
     

     View Slide

108. fun onStart() {
     events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     .subscribe { viewModel ->
     nameView.hint = if (viewModel.prefixedName.name.isEmpty()) "Set your name" else ""
     nameView.text = viewModel.prefixedName.compute()
     // rendering other stuff
     }
     }
     fun onSetNameDialogResult(newName: String) {
     events.onNext(EditName(newName))
     }
     

     View Slide

109. events // Observable
     .subscribe { viewModel ->
     }
     

     View Slide

110. events // Observable
     
     .subscribe { viewModel ->
     }
     

     View Slide

111. View Slide

112. Passing events to the Presenter
     

     View Slide

113. Option A
     Passing events to the Presenter
     

     View Slide

114. events
     .subscribe { viewModel ->
     }
     class ProfilePresenter : Consumer {
     }
     View
     Presenter
     

     View Slide

115. events
     .subscribe { viewModel ->
     }
     class ProfilePresenter : Consumer {
     override fun accept(event: Event) {
     }
     }
     View
     Presenter
     

     View Slide

116. events.subscribe(presenter)
     presenter.something().subscribe { viewModel -> }
     class ProfilePresenter : Consumer {
     override fun accept(event: Event) {
     }
     }
     View
     Presenter
     

     View Slide

117. class ProfilePresenter : Consumer {
     override fun accept(event: Event) {
     event.flatMap {}
     }
     }
     View
     Presenter
     events.subscribe(presenter)
     presenter.something().subscribe { viewModel -> }
     

     View Slide

118. Option B
     Passing events to the Presenter
     

     View Slide

119. events.
     .subscribe { viewModel ->
     }
     class ProfilePresenter(val events:Observable) {
     }
     View
     Presenter
     

     View Slide

120. events.
     .subscribe { viewModel ->
     }
     class ProfilePresenter(val events:Observable) {
     init {
     events.publish { events -> }
     }
     }
     View
     Presenter
     

     View Slide

121. presenter(events)
     .subscribe { viewModel ->
     }
     class ProfilePresenter(val events:Observable) {
     init {
     events.publish { events -> }
     }
     }
     View
     Presenter
     

     View Slide

122. Option C
     Passing events to the Presenter
     

     View Slide

123. presenter.viewModels(events)
     .subscribe { viewModel ->
     }
     class ProfilePresenter {
     fun viewModels(events: Observable) {
     events.publish { events -> }
     }
     }
     View
     Presenter
     

     View Slide

124. View Slide

125. Passing view models
     to the View
     

     View Slide

126. Option A
     Passing view models to the View
     

     View Slide

127. presenter.viewmodels()
     .subscribe { viewModel ->
     }
     class ProfilePresenter {
     fun viewmodels(): Observable {
     }
     }
     View
     Presenter
     

     View Slide

128. Option B
     Passing view models to the View
     

     View Slide

129. presenter
     .subscribe { viewModel ->
     }
     class ProfilePresenter: Observable() {
     override fun subscribeActual(observer: Observer) {
     }
     }
     View
     Presenter
     

     View Slide

130. Option C
     Passing view models to the View
     

     View Slide

131. presenter
     .subscribe()
     class ProfilePresenter: ObservableSource {
     override fun subscribe(observer: Observer) {
     }
     }
     View
     Presenter
     

     View Slide

132. presenter
     .subscribe(object : Observer {
     override fun onComplete() {}
     override fun onSubscribe(d: Disposable) {}
     override fun onNext(t: ViewModel) {}
     override fun onError(e: Throwable) {}
     })
     class ProfilePresenter: ObservableSource {
     override fun subscribe(observer: Observer) {
     }
     }
     View
     Presenter
     

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133. Observable.wrap(presenter)
     .subscribe { viewModel ->
     }
     class ProfilePresenter: ObservableSource {
     override fun subscribe(observer: Observer) {
     }
     }
     View
     Presenter
     

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134. View Slide

135. Writing is good.
     Thinking is better.
     

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136. fun presenter()
     

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137. fun presenter(events: Observable)
     

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138. fun presenter(events: Observable): Observable
     

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139. interface ObservableTransformer {
     /**
     * Applies a function to the upstream Observable and returns an ObservableSource with
     * optionally different element type.
     */
     fun apply(upstream: Observable): ObservableSource
     }
     

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140. interface ObservableTransformer {
     fun apply(upstream: Observable): ObservableSource
     }
     

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141. interface ObservableTransformer {
     fun apply(events: Observable): ObservableSource
     }
     

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142. interface ObservableTransformer {
     fun apply(events: Observable): ObservableSource
     }
     

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143. class Presenter: ObservableTransformer {
     fun apply(events: Observable): ObservableSource
     }
     

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144. class Presenter: ObservableTransformer {
     fun apply(events: Observable): ObservableSource
     }
     events
     .compose(presenter)
     .subscribe { viewModel ->
     }
     View
     Presenter
     

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145. class Presenter: ObservableTransformer {
     fun apply(events: Observable): ObservableSource
     }
     val testObserver = events // PublishSubject
     .compose(presenter)
     .test() // TestObserver
     Test
     Presenter
     

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146. class Presenter: ObservableTransformer {
     fun apply(events: Observable): ObservableSource
     }
     val testObserver = events // PublishSubject
     .compose(presenter)
     .test() // TestObserver
     events.onNext(EditName("Georges"))
     testObserver.assertValue(ViewModel())
     Test
     Presenter
     

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147. Presenter
     • Don't break the stream
     • Don't start work until observed
     • Doesn't handle disposables*
     • Has one entry point
     • Has one exit point
     

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148. View Slide

149. Thinking is good.
     Config Changes is better.
     

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150. class ProfilePresenter {
     }
     View
     Presenter
     

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151. class ProfilePresenter {
     val events = PublishSubject.create()
     fun passEvents(events: Observable) {
     events.subscribe(this.events)
     }
     }
     View
     Presenter
     

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152. class ProfilePresenter {
     val events = PublishSubject.create()
     fun passEvents(events: Observable) {
     events.subscribe(this.events)
     }
     fun viewModels() {
     return events.businessLogic()
     }
     }
     View
     Presenter
     

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153. class ProfilePresenter {
     val events = PublishSubject.create()
     fun passEvents(events: Observable) {
     events.subscribe(this.events)
     }
     private val vmObservable : Observable by lazy(NONE) {
     events.businessLogic()
     .replay(1)
     .autoConnect(0)
     }
     fun viewModels() = vmObservable
     }
     View
     Presenter
     

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154. presenter.viewModels()
     .subscribe { viewModel ->
     }
     View
     Presenter
     class ProfilePresenter {
     val events = PublishSubject.create()
     fun passEvents(events: Observable) {
     events.subscribe(this.events)
     }
     private val vmObservable : Observable by lazy(NONE) {
     events.businessLogic()
     .replay(1)
     .autoConnect(0)
     }
     fun viewModels() = vmObservable
     }
     

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155. presenter.viewModels()
     .subscribe { viewModel ->
     }
     presenter.passEvents(events)
     View
     Presenter
     class ProfilePresenter {
     val events = PublishSubject.create()
     fun passEvents(events: Observable) {
     events.subscribe(this.events)
     }
     private val vmObservable : Observable by lazy(NONE) {
     events.businessLogic()
     .replay(1)
     .autoConnect(0)
     }
     fun viewModels() = vmObservable
     }
     

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156. View Slide

157. Unidirectional
     Data
     Flow
     

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158. VIEW
     PRESENTER
     

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159. VIEW
     PRESENTER (BUSINESS LOGIC)
     READING
     WRITING
     

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160. VIEW
     PRESENTER (BUSINESS LOGIC)
     VIEW (READING) VIEW (WRITING)
     

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161. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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162. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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163. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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164. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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165. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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166. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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167. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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168. VIEW (READING)
     VIEW (WRITING)
     PRESENTER (BUSINESS LOGIC)
     

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169. View Slide

170. New Feature?
     No Problem.
     

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171. sealed class Event {
     data class EditName(val newName: String) : Event()
     }
     data class ViewModel(
     val stuff: Any?,
     val prefixedName: PrefixedName
     )
     class ProfileViewRemix {
     fun onStart() {
     events
     .compose(presenter)
     .subscribe { viewModel ->
     // rendering view model
     }
     }
     }
     

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172. sealed class Event {
     data class EditName(val newName: String) : Event()
     }
     data class ViewModel(
     val stuff: Any?,
     val prefixedName: PrefixedName
     )
     class ProfileViewRemix {
     fun onStart() {
     events
     .compose(presenter)
     .subscribe { viewModel ->
     // rendering view model
     }
     }
     }
     

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173. sealed class Event {
     data class EditName(val newName: String) : Event()
     data class ChangeAvatar(val picture: File) : Event()
     }
     data class ViewModel(
     val stuff: Any?,
     val prefixedName: PrefixedName
     )
     class ProfileViewRemix {
     fun onStart() {
     events
     .compose(presenter)
     .subscribe { viewModel ->
     // rendering view model
     }
     }
     }
     

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174. sealed class Event {
     data class EditName(val newName: String) : Event()
     data class ChangeAvatar(val picture: File) : Event()
     }
     data class ViewModel(
     val stuff: Any?,
     val prefixedName: PrefixedName,
     val avatarUri: Uri
     )
     class ProfileViewRemix {
     fun onStart() {
     events
     .compose(presenter)
     .subscribe { viewModel ->
     // rendering view model
     }
     }
     }
     

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175. sealed class Event {
     data class EditName(val newName: String) : Event()
     data class ChangeAvatar(val picture: File) : Event()
     }
     data class ViewModel(
     val stuff: Any?,
     val prefixedName: PrefixedName,
     val avatarUri: Uri
     )
     class ProfileViewRemix {
     fun onStart() {
     events
     .compose(presenter)
     .subscribe { viewModel ->
     // rendering view model
     Picasso.get().load(viewModel.avatarUri).into(avatarView)
     }
     }
     }
     

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176. class ProfilePresenter : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance()
     .switchMap { event ->
     appService.setName(event.newName).map { response ->
     when {
     response.isValid -> NameValid(response.name)
     response.isInvalid -> NameInvalid.also { navigator.goTo(response) }
     }
     }
     .startWith(NameValid(event.newName))
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     }
     }
     

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177. class ProfilePresenter : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance().logic()
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     }
     }
     

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178. class ProfilePresenter : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance().logic()
     events.filterIsInstance()
     .switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     }
     }
     

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179. class ProfilePresenter : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance().logic()
     events.filterIsInstance()
     .switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     .onErrorReturn { throwable -> AvatarInvalid(throwable) }
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     }
     })
     }
     }
     

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180. class ProfilePresenter : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance().logic()
     events.filterIsInstance()
     .switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     .onErrorReturn { throwable -> AvatarInvalid(throwable) }
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     is AvatarValid -> previous.copy(avatarUri = result.uri)
     }
     })
     }
     }
     

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181. class ProfilePresenter : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance().logic()
     events.filterIsInstance()
     .switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     .onErrorReturn { throwable -> AvatarInvalid(throwable) }
     }
     )
     }
     .mergeWith(appService.profile().map(::ProfileResult))
     .scan(ViewModel(stuff = null, prefixedName = PrefixedName("", "")),
     BiFunction { previous: ViewModel, result: Result ->
     when (result) {
     is NameValid -> previous.copy(prefixedName = previous.prefixedName.copy(name = result.name))
     is NameInvalid -> previous
     is ProfileResult -> previous.copy(
     stuff = result.profile,
     prefixedName = PrefixedName(result.profile.prefix, result.profile.name)
     )
     is AvatarValid -> previous.copy(avatarUri = result.uri)
     is AvatarInvalid -> TODO()
     }
     })
     }
     }
     

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182. View Slide

183. Architecture forced us to separate concerns
     

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184. Architecture forced us to separate concerns
     No need to touch existing code
     

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185. Architecture forced us to separate concerns
     No need to touch existing code
     Easy to test
     

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186. Architecture forced us to separate concerns
     No need to touch existing code
     Easy to test
     Easy to review
     

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187. View Slide

188. Extension Function ?
     

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189. events.filterIsInstance()
     .switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     }
     

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190. events.filterIsInstance().changeAvatar()
     private fun Observable.changeAvatar(): Observable {
     return switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     }
     }
     events.filterIsInstance()
     .switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     }
     

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191. events.filterIsInstance().changeAvatar()
     private fun Observable.changeAvatar(): Observable {
     return switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     }
     }
     events.filterIsInstance()
     .switchMap { event ->
     appService.changeAvatar(event.picture)
     .map { response -> AvatarValid(response.uri) }
     }
     

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192. View Slide

193. Navigation
     

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194. interface Navigator {
     fun goTo(screen: Any)
     }
     

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195. interface Navigator {
     fun goTo(screen: Any)
     }
     interface Launcher {
     fun shareText(text: String): Boolean
     fun launchUrl(url: String): Boolean
     fun launchApp(packageName: String): Boolean
     }
     

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196. interface Navigator {
     fun goTo(screen: Any)
     }
     

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197. interface Navigator {
     fun goTo(screen: Any)
     }
     class ProfilePresenter(
     private val navigator: Navigator
     ) : ObservableTransformer {
     }
     

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198. interface Navigator {
     fun goTo(screen: Any)
     }
     class ProfilePresenter(
     private val navigator: Navigator
     ) : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance().goTo()
     )
     }
     }
     }
     

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199. interface Navigator {
     fun goTo(screen: Any)
     }
     class ProfilePresenter(
     private val navigator: Navigator
     ) : ObservableTransformer {
     override fun apply(events: Observable): ObservableSource {
     return events.publish { events ->
     Observable.merge(
     events.filterIsInstance().goTo()
     )
     }
     }
     private fun Observable.goTo(): Observable {
     return doOnNext {
     navigator.goTo(SomeScreen)
     }
     .ignoreElements()
     .toObservable()
     }
     }
     

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200. inline fun Observable.consumeOnNext(
     crossinline sideEffect: (T) -> Unit
     ): Observable {
     return doOnNext { sideEffect(it) }
     .ignoreElements()
     .toObservable()
     }
     private fun Observable.goTo(): Observable {
     return consumeOnNext {
     navigator.goTo(SomeScreen)
     }
     }
     

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201. class FakeNavigator : Navigator {
     private val navigatedScreens = ArrayDeque()
     override fun goTo(screen: Any) {
     navigatedScreens.add(screen)
     }
     fun takeNext() = navigatedScreens.pop()!!
     fun isEmpty() = navigatedScreens.isEmpty()
     }
     events.accept(Event)
     assertThat(navigator.takeNextScreen()).isEqualTo(ExpectedScreen)
     

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202. View Slide

203. Gotta Immutate 'em All!
     Unidirectional Data Flow
     Side-Effects Isolation
     

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204. Benoît Quenaudon @oldergod
     Fin
     

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