How to MVI?

Presented on April '18 at BlrDroid 101.
https://www.meetup.com/blrdroid/events/249149873/

Transcript

1. How to MVI?
   Ragunath Jawahar
   ragunathjawahar / Medium • Twitter • GitHub
   

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2. *This statement is architecture / platform agnostic
   

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3. Why?
   Courtesy pexels.com/@goumbik
   

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4. Why?
   

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5. Background
   1. Several iterations since April ’17
   2. Maximize testability and minimize code
   3. Offline-first app with device capabilities
   4. Both Android and iOS
   

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6. Testing Goals
   UI Tests
   Instrumented Tests
   Unit Tests
   **Not to scale
   

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7. Testing Goals
   UI Tests
   Instrumented Tests
   Unit Tests
   **Not to scale
   

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8. Testing Goals
   UI Tests
   Instrumented Tests
   Unit Tests
   **Not to scale
   

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9. Testing Goals
   UI Tests
   Instrumented Tests
   Unit Tests
   **Not to scale
   

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10. Benefits
    1. Predictable
    2. Platform Agnostic
    3. User-centric
    4. Reactive (Responsive / Resilient / Elastic / Message Driven)
    5. Unidirectional
    

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11. Model
    Presenter
    View
    

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12. Toolbox (Subjective)
    • Kotlin
    • RxJava
    • RxAndroid
    • RxKotlin (Optional)
    • RxBinding
    • Retrofit
    • Room / SQL Brite
    • JUnit
    • Truth
    • Mockito
    • Espresso
    

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13. Model ● View ● Intention
    

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14. View
    Model
    Intention
    

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15. EVERYTHING IS A
    STREAM
    Courtesy parkerblog.wordpress.com
    

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16. Intention
    

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17. Intent(ion) is a component whose sole
    responsibility is to translate user input
    events into model-friendly events.
    —André Staltz
    

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18. Intent(ion) is a component whose sole
    responsibility is to translate user input
    events into model-friendly events.
    —André Staltz
    

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19. Intent(ion) is a component whose sole
    responsibility is to translate user input
    events into model-friendly events.
    —André Staltz
    

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20. View
    Model
    Intention
    

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23. CounterIntentions.kt
    

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24. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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25. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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26. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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27. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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28. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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29. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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30. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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31. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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32. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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33. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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34. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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35. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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36. class CounterIntentions(
    private val incrementClicks: Observable,
    private val incrementBy5Clicks: Observable,
    private val decrementClicks: Observable,
    private val resetClicks: Observable
    ) {
    fun increment(): Observable =
    incrementClicks.map { +1 }
    // increment by 5 …
    fun decrement(): Observable =
    decrementClicks.map { -1 }
    fun reset(): Observable =
    resetClicks
    }
    

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37. Testing?
    

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38. Model
    

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39. View
    Model
    Intention
    

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40. Courtesy 123Countries.com
    State Model
    

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41. (Single Atom) State
    • Represents the state of your model
    • Should be normalized
    • UI state can always be derived from SAS, but not
    the other way around
    

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42. State Reducer
    Reducer
    State
    New
    State
    Signal
    

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43. CounterState.kt
    

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44. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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45. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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46. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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47. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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48. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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49. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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50. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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51. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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52. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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53. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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54. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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55. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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56. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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57. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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58. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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59. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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60. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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61. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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62. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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63. @Parcelize data class CounterState(
    val counter: Int
    ) : Parcelable {
    companion object {
    val ZERO = CounterState(0)
    }
    fun add(number: Int): CounterState =
    this.copy(counter = counter + number)
    fun reset(): CounterState =
    CounterState.ZERO
    }
    

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64. CounterModel.kt
    

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65. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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66. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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67. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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68. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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69. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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70. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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71. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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72. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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73. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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74. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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75. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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76. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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77. object CounterModel {
    fun bind(
    intentions: CounterIntentions,
    bindings: Observable,
    states: Observable
    ): Observable {
    val numbers = Observable.merge(
    intentions.increment(), intentions.incrementBy5(),
    intentions.decrement()
    )
    return Observable.merge(
    newBindingUseCase(bindings),
    restoredBindingUseCase(bindings, states),
    incrementDecrementUseCase(numbers, states),
    resetUseCase(intentions.reset())
    )
    }
    // More functions…
    }
    

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78. Use Case - New Binding
    private fun newBindingUseCase(
    bindings: Observable
    ): Observable {
    return bindings
    .filter { it == Binding.NEW }
    .map { CounterState.ZERO }
    }
    

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79. Use Case - New Binding
    private fun newBindingUseCase(
    bindings: Observable
    ): Observable {
    return bindings
    .filter { it == Binding.NEW }
    .map { CounterState.ZERO }
    }
    

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80. Use Case - New Binding
    private fun newBindingUseCase(
    bindings: Observable
    ): Observable {
    return bindings
    .filter { it == Binding.NEW }
    .map { CounterState.ZERO }
    }
    

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81. Use Case - New Binding
    private fun newBindingUseCase(
    bindings: Observable
    ): Observable {
    return bindings
    .filter { it == Binding.NEW }
    .map { CounterState.ZERO }
    }
    

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82. Use Case - New Binding
    private fun newBindingUseCase(
    bindings: Observable
    ): Observable {
    return bindings
    .filter { it == Binding.NEW }
    .map { CounterState.ZERO }
    }
    

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83. Use Case - New Binding
    private fun newBindingUseCase(
    bindings: Observable
    ): Observable {
    return bindings
    .filter { it == Binding.NEW }
    .map { CounterState.ZERO }
    }
    

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84. Use Case - Restored Binding
    private fun restoredBindingUseCase(
    bindings: Observable,
    states: Observable
    ): ObservableSource {
    return bindings
    .filter { it == Binding.RESTORED }
    .withLatestFrom(states) {
    _, previousState -> previousState
    }
    }
    

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85. Use Case - Restored Binding
    private fun restoredBindingUseCase(
    bindings: Observable,
    states: Observable
    ): ObservableSource {
    return bindings
    .filter { it == Binding.RESTORED }
    .withLatestFrom(states) {
    _, previousState -> previousState
    }
    }
    

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86. Use Case - Restored Binding
    private fun restoredBindingUseCase(
    bindings: Observable,
    states: Observable
    ): ObservableSource {
    return bindings
    .filter { it == Binding.RESTORED }
    .withLatestFrom(states) {
    _, previousState -> previousState
    }
    }
    

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87. Use Case - Restored Binding
    private fun restoredBindingUseCase(
    bindings: Observable,
    states: Observable
    ): ObservableSource {
    return bindings
    .filter { it == Binding.RESTORED }
    .withLatestFrom(states) {
    _, previousState -> previousState
    }
    }
    

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88. Use Case - Restored Binding
    private fun restoredBindingUseCase(
    bindings: Observable,
    states: Observable
    ): ObservableSource {
    return bindings
    .filter { it == Binding.RESTORED }
    .withLatestFrom(states) {
    _, previousState -> previousState
    }
    }
    

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89. Use Case - Restored Binding
    private fun restoredBindingUseCase(
    bindings: Observable,
    states: Observable
    ): ObservableSource {
    return bindings
    .filter { it == Binding.RESTORED }
    .withLatestFrom(states) {
    _, previousState -> previousState
    }
    }
    

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90. Use Case - Increment / Decrement
    private fun incrementDecrementUseCase(
    numbers: Observable,
    states: Observable
    ): Observable {
    return numbers.withLatestFrom(states) {
    number, previousState -> previousState.add(number)
    }
    }
    

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91. Use Case - Increment / Decrement
    private fun incrementDecrementUseCase(
    numbers: Observable,
    states: Observable
    ): Observable {
    return numbers.withLatestFrom(states) {
    number, previousState -> previousState.add(number)
    }
    }
    

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92. Use Case - Increment / Decrement
    private fun incrementDecrementUseCase(
    numbers: Observable,
    states: Observable
    ): Observable {
    return numbers.withLatestFrom(states) {
    number, previousState -> previousState.add(number)
    }
    }
    

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93. Use Case - Increment / Decrement
    private fun incrementDecrementUseCase(
    numbers: Observable,
    states: Observable
    ): Observable {
    return numbers.withLatestFrom(states) {
    number, previousState -> previousState.add(number)
    }
    }
    

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94. Use Case - Increment / Decrement
    private fun incrementDecrementUseCase(
    numbers: Observable,
    states: Observable
    ): Observable {
    return numbers.withLatestFrom(states) {
    number, previousState -> previousState.add(number)
    }
    }
    

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95. Use Case - Increment / Decrement
    private fun incrementDecrementUseCase(
    numbers: Observable,
    states: Observable
    ): Observable {
    return numbers.withLatestFrom(states) {
    number, previousState -> previousState.add(number)
    }
    }
    

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96. Use Case - Reset
    private fun resetUseCase(
    reset: Observable
    ): Observable {
    return reset.map { CounterState.ZERO }
    }
    

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97. Use Case - Reset
    private fun resetUseCase(
    reset: Observable
    ): Observable {
    return reset.map { CounterState.ZERO }
    }
    

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98. Use Case - Reset
    private fun resetUseCase(
    reset: Observable
    ): Observable {
    return reset.map { CounterState.ZERO }
    }
    

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99. Use Case - Reset
    private fun resetUseCase(
    reset: Observable
    ): Observable {
    return reset.map { CounterState.ZERO }
    }
    

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100. Use Case - Reset
     private fun resetUseCase(
     reset: Observable
     ): Observable {
     return reset.map { CounterState.ZERO }
     }
     

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101. Don’t scan() (Recommendation)
     • Introduces additional abstraction because it requires
     homogeneous streams
     

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102. View
     

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103. View
     Model
     Intention
     

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104. CounterView.kt
     

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105. interface CounterView {
     fun displayCounter(value: Int)
     }
     

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106. interface CounterView {
     fun displayCounter(value: Int)
     }
     

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107. CounterViewDriver.kt
     

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108. class CounterViewDriver : ViewDriver {
     override fun render(view: CounterView, state: CounterState) {
     view.displayCounter(state.counter)
     }
     }
     

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109. class CounterViewDriver : ViewDriver {
     override fun render(view: CounterView, state: CounterState) {
     view.displayCounter(state.counter)
     }
     }
     

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110. class CounterViewDriver : ViewDriver {
     override fun render(view: CounterView, state: CounterState) {
     view.displayCounter(state.counter)
     }
     }
     

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111. class CounterViewDriver : ViewDriver {
     override fun render(view: CounterView, state: CounterState) {
     view.displayCounter(state.counter)
     }
     }
     

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112. class CounterViewDriver : ViewDriver {
     override fun render(view: CounterView, state: CounterState) {
     view.displayCounter(state.counter)
     }
     }
     

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113. class CounterViewDriver : ViewDriver {
     override fun render(view: CounterView, state: CounterState) {
     view.displayCounter(state.counter)
     }
     }
     

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114. Learnings
     • RxJava yields better results with a reactive architecture
     • You don’t need lifecycle events (most of the time)
     • UI tests are necessary
     • Collaboration between mobile teams is possible and fun
     

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115. Pros
     • Wholistic
     • Testable
     • Easy to debug
     • Reduction in the number of unknowns
     

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116. Cons
     

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117. Cons In Words
     • Learning curve
     • Buy-in from team / tech leaders
     • Hiring (as of today)
     

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119. References
     • https://www.youtube.com/watch?v=1zj7M1LnJV4
     • https://cycle.js.org/getting-started.html
     • https://egghead.io/courses/cycle-js-fundamentals
     • https://redux.js.org
     • https://egghead.io/courses/getting-started-with-redux
     • https://github.com/ragunathjawahar/kitchen-sink
     

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120. Medium • Twitter • GitHub
     @ragunathjawahar
     

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