Code Generating Your Way to Happiness

This talk explores how code gen can be used to eliminate a class of issues and sources of developer boilerplate, as well as walking through some popular libraries and uber-specific use cases.

Transcript

1. Code generating your
   way to happiness
   Zac Sweers - Uber
   @pandanomic
   

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2. "Code generating your
   way to happiness."
   

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3. FileSpec.builder("", "Presentation")
   .addComment("Code generating your way to happiness.")
   .addAnnotation(AnnotationSpec.builder(Author::class)
   .addMember("name", "%S", "Zac Sweers")
   .useSiteTarget(FILE)
   .build())
   .build()
   

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4. FileSpec.builder("", "Presentation")
   .addComment("Code generating your way to happiness.")
   .addAnnotation(AnnotationSpec.builder(Author::class)
   .addMember("name", "%S", "Zac Sweers")
   .useSiteTarget(FILE)
   .build())
   .build()
   

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5. FileSpec.builder("", "Presentation")
   .addComment("Code generating your way to happiness.")
   .addAnnotation(AnnotationSpec.builder(Author::class)
   .addMember("name", "%S", "Zac Sweers")
   .useSiteTarget(FILE)
   .build())
   .build()
   

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6. FileSpec.builder("", "Presentation")
   .addComment("Code generating your way to happiness.")
   .addAnnotation(AnnotationSpec.builder(Author::class)
   .addMember("name", "%S", "Zac Sweers")
   .useSiteTarget(FILE)
   .build())
   .build()
   

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7. FileSpec.builder("", "Presentation")
   .addComment("Code generating your way to happiness.")
   .addAnnotation(AnnotationSpec.builder(Author::class)
   .addMember("name", "%S", "Zac Sweers")
   .useSiteTarget(FILE)
   .build())
   .build()
   

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8. FileSpec.builder("", "Presentation")
   .addComment("Code generating your way to happiness.")
   .addAnnotation(AnnotationSpec.builder(Author::class)
   .addMember("name", "%S", "Zac Sweers")
   .useSiteTarget(FILE)
   .build())
   .build()
   

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9. // Code generating your way to happiness.
   @file:Author(name = "Zac Sweers")
   Presentation.kt
   

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10. FileSpec.builder("", "Presentation")a
    .addComment("Code generating your way to happiness.")
    .addAnnotation(AnnotationSpec.builder(Author::class)
    .addMember("name", "%S", "Zac Sweers")
    .useSiteTarget(FILE)
    .build())
    .build()b
    

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11. FileSpec.builder("", presentationName)a
    .addComment("Code generating your way to happiness.")
    .addAnnotation(AnnotationSpec.builder(Author::class)
    .addMember("name", "%S", "Zac Sweers")
    .useSiteTarget(FILE)
    .build())
    .build()b
    

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12. FileSpec.builder("", presentationName)a
    .addComment(comment)
    .addAnnotation(AnnotationSpec.builder(Author::class)
    .addMember("name", "%S", "Zac Sweers")
    .useSiteTarget(FILE)
    .build())
    .build()b
    

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13. FileSpec.builder("", presentationName)a
    .addComment(comment)
    .addAnnotation(AnnotationSpec.builder(Author::class)
    .addMember("name", "%S", author)
    .useSiteTarget(FILE)
    .build())
    .build()b
    

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14. presentations.onEach { (presentationName, comment, author) ->
    FileSpec.builder("", presentationName)a
    .addComment(comment)
    .addAnnotation(AnnotationSpec.builder(Author::class)
    .addMember("name", "%S", author)
    .useSiteTarget(FILE)
    .build())
    .build()b
    }
    

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15. conferences
    .flatMap { it.presentations }
    .onEach { (presentationName, comment, author) ->
    FileSpec.builder("", presentationName)a
    .addComment(comment)
    .addAnnotation(AnnotationSpec.builder(Author::class)
    .addMember("name", "%S", author)
    .useSiteTarget(FILE)
    .build())
    .build()b
    }
    Boilerplate
    

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16. Benefits
    • Boilerplate avoidance
    

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17. Benefits
    • Boilerplate avoidance
    • Correctness
    

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18. Correctness
    class Person(val firstName: String, val lastName: String)m
    

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19. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    }l
    

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20. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    }k
    }l
    

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21. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    }k
    }l
    

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22. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    return Person(firstName, lastName)j
    }k
    }l
    

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23. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    }n
    return Person(firstName, lastName)j
    }k
    }l
    

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24. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    when (reader.nextName()) {f
    }o
    }n
    return Person(firstName, lastName)j
    }k
    }l
    

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25. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    when (reader.nextName()) {f
    "firstName" -> firstName = reader.nextString()g
    }o
    }n
    return Person(firstName, lastName)j
    }k
    }l
    

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26. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    when (reader.nextName()) {f
    "firstName" -> firstName = reader.nextString()g
    "lastName" -> lastName = reader.nextString()h
    }o
    }n
    return Person(firstName, lastName)j
    }k
    }l
    

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27. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    when (reader.nextName()) {f
    "firstName" -> firstName = reader.nextString()g
    "lastName" -> lastName = reader.nextString()h
    else -> reader.skipValue()i
    }o
    }n
    return Person(firstName, lastName)j
    }k
    }l
    

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28. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    when (reader.nextName()) {f
    "firstname" -> firstName = reader.nextString()g
    "lastName" -> lastName = reader.nextString()h
    else -> reader.skipValue()i
    }o
    }n
    return Person(firstName, lastName)j
    }k
    }l
    

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29. class Person(val firstName: String, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    when (reader.nextName()) {f
    "firstname" -> firstName = reader.nextString()g
    "lastName" -> lastName = reader.nextString()h
    else -> reader.skipValue()i
    }o
    }n
    return Person(lastName, firstName)j
    }k
    }l
    

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30. class Person(val firstName: String?, val lastName: String)m
    class PersonJsonAdapter : JsonAdapter() {a
    override fun fromJson(reader: JsonReader): Person? {b
    lateinit var firstName: Stringc
    lateinit var lastName: Stringd
    while (reader.hasNext()) {e
    when (reader.nextName()) {f
    "firstname" -> firstName = reader.nextString()g
    "lastName" -> lastName = reader.nextString()h
    else -> reader.skipValue()i
    }o
    }n
    return Person(lastName, firstName)j
    }k
    }l
    

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31. class Person(val firstName: String, val lastName: String)m
    

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32. class Person(val firstName: String, val lastName: String)m
    class City(val name: String, val country: String)
    class Vehicle(val licensePlate: String)
    class Restaurant(val type: String, val address: Address)
    class Payment(val cardNumber: String, val type: String)
    class TipAmount(val value: Double)
    class Rating(val numStars: Int)
    class Correctness(val confidence: Double)
    

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33. Benefits
    • Boilerplate
    • Correctness
    

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34. Recognizing
    • Boilerplate
    • Correctness
    Boilerplate
    Ceremony
    Value types!
    Especially if you have specs!
    Tests too
    

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35. Tools
    

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36. Tools
    •JavaPoet/KotlinPoet
    

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37. Tools
    •JavaPoet/KotlinPoet
    •Templating
    

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38. Tools
    •JavaPoet/KotlinPoet
    •Templating
    •SPI
    

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39. Tools
    •JavaPoet/KotlinPoet
    •Templating
    •SPI
    •Compile Testing
    

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40. Tools
    •JavaPoet/KotlinPoet
    •Templating
    •SPI
    •Compile Testing
    •Annotation
    Processing (APT)
    

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41. Tools
    •JavaPoet/KotlinPoet
    •Templating
    •SPI
    •Compile Testing
    •Annotation
    Processing (APT)
    •Gradle
    

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42. Examples
    

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43. Butter Knife
    

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44. Butter Knife
    TextView title;a
    void onCreate(Bundle savedInstanceState) {c
    title = findViewById(R.id.title);d
    }f
    

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45. Butter Knife
    TextView title;a
    ImageView icon;b
    void onCreate(Bundle savedInstanceState) {c
    title = findViewById(R.id.title);d
    }f
    

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46. Butter Knife
    TextView title;a
    ImageView icon;b
    void onCreate(Bundle savedInstanceState) {c
    title = findViewById(R.id.title);d
    icon = findViewById(R.id.icon);e
    }f
    

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47. Butter Knife
    @BindView(R.id.title) TextView title;a
    @BindView(R.id.icon) ImageView icon;b
    void onCreate(Bundle savedInstanceState) {c
    ButterKnife.bind(this);
    }f
    

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48. Butter Knife
    @BindView(R.id.title) TextView title;a
    @BindView(R.id.icon) ImageView icon;b
    @BindView(R.id.button) Button button;
    void onCreate(Bundle savedInstanceState) {c
    ButterKnife.bind(this);g
    }f
    

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49. Butter Knife
    @BindView(R.id.title) TextView title;a
    void onCreate(Bundle savedInstanceState) {c
    ButterKnife.bind(this);
    }f
    

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50. @BindView(R.id.title) TextView title;
    

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51. // FooActivity
    @BindView(R.id.title) TextView title;
    

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52. // FooActivity
    @BindView(R.id.title) TextView title;
    

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53. // FooActivity
    @BindView(R.id.title) TextView title;
    

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54. // FooActivity
    @BindView(2131361859) TextView title;
    

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55. // FooActivity
    @BindView(2131361859) TextView title;
    

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56. // FooActivity
    @BindView(2131361859) TextView title;
    

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57. // FooActivity
    @BindView(2131361859) TextView title;
    

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58. ViewBinding(
    target = "FooActivity",
    id = 2131361859,
    name = "title",
    type = "field",
    viewType = TextView.class
    )
    

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59. public final class FooActivity_ViewBinding implements Unbinder {
    private FooActivity target;
    @UiThread
    public FooActivity_ViewBinding(FooActivity target, View source) {
    this.target = target;
    target.title = Utils.findRequiredViewAsType(source,
    2131361859, // R.id.title
    "field 'title'",
    TextView.class);
    }a
    }b
    

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60. @BindView(R.id.title) TextView title;a
    void onCreate(Bundle savedInstanceState) {c
    ButterKnife.bind(this);
    }f
    public final class FooActivity_ViewBinding implements Unbinder {
    private FooActivity target;
    @UiThread
    public FooActivity_ViewBinding(FooActivity target, View source) {
    this.target = target;
    target.title = Utils.findRequiredViewAsType(source,
    2131361859, // R.id.title
    "field 'title'",
    TextView.class);
    }a
    }b
    APT Runtime
    

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61. Butter Knife
    

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62. RxBinding
    

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63. RxBinding
    KotlinGenTask
    Generates
    all
    these!
    

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64. public static Observable clicks(View view) {
    return new ViewClickObservable(view);
    }
    

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65. fun View.clicks(): Observable = RxView.clicks(this)a
    

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66. fun View.clicks(): Observable = RxView.clicks(this)a
    

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67. fun View.clicks(): Observable = RxView.clicks(this)a
    public static Observable clicks(View view) {
    return new ViewClickObservable(view);
    }b
    

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68. fun View.clicks(): Observable = RxView.clicks(this)a
    public static Observable clicks(View view) {
    return new ViewClickObservable(view);
    }b
    

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69. fun View.clicks(): Observable = RxView.clicks(this)a
    public static Observable clicks(View view) {
    return new ViewClickObservable(view);
    }b
    

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70. fun View.clicks(): Observable = RxView.clicks(this)a
    public static Observable clicks(View view) {
    return new ViewClickObservable(view);
    }b
    

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71. fun View.clicks(): Observable = RxView.clicks(this)a
    public static Observable clicks(View view) {
    return new ViewClickObservable(view);
    }b
    

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72. fun View.clicks(): Observable = RxView.clicks(this)a
    public static Observable clicks(View view) {a
    return new ViewClickObservable(view);
    }b
    

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73. public static Observable clicks(View view) {a
    return new ViewClickObservable(view);
    }b
    

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74. // RxView
    public static Observable clicks(View view) {a
    return new ViewClickObservable(view);
    }b
    

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75. BindingMethod(
    target = "RxView",
    name = "clicks",
    type = View.class,
    returnType = "Observable"
    )b
    

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76. BindingMethod(
    target = "RxView",
    name = "clicks",
    type = View.class,
    returnType = "Observable"
    )b
    

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77. fun View.clicks(): Observable = RxView.clicks(this)a
    

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78. RxBinding
    

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79. Service Gen
    

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80. @AutoValuea
    abstract class Rider {b
    abstract String uuid();c
    abstract String firstName();d
    abstract String lastName();e
    abstract Address address();f
    }g
    Service Gen
    

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81. interface UberService {a
    @GET("/rider")b
    Rider getRider()c
    }d
    

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82. interface UberService {a
    @GET("/rider")b
    Single getRider()c
    }d
    

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83. struct Rider {
    1: required string uuid;
    2: required string firstName;
    3: required string lastName;
    4: optional Address address;
    }
    

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84. @AutoValuea
    abstract class Rider {b
    abstract String uuid();c
    abstract String firstName();d
    abstract String lastName();e
    abstract Address address();f
    }g
    

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85. @AutoValuea
    abstract class Rider {b
    abstract String uuid();c
    abstract String firstName();d
    abstract String lastName();e
    abstract Address address();f
    static JsonAdapter jsonAdapter(Moshi moshi) {
    return new AutoValue_Rider.JsonAdapter(moshi);
    }
    }g
    

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86. service UberService {a
    Rider getRider()
    }b
    

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87. service UberService {a
    Rider getRider() (path="/rider")
    }b
    

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88. interface UberService {
    @GET("/rider")
    Single getRider()
    }
    

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89. service UberService {
    Rider getRider()
    }
    

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90. astruct Rider
    

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91. astruct Rider
    struct City
    struct Vehicle
    struct Restaurant
    struct Payment
    struct TipAmount
    struct Rating
    

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92. astruct Rider
    struct City
    struct Vehicle
    struct Restaurant
    struct Payment
    struct TipAmount
    struct Rating
    // And 6000 more
    

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93. class ModelsAdapterFactory
    implements JsonAdapter.Factory {
    @Override
    public JsonAdapter> create(Type type,
    Set extends Annotation> annotations,
    Moshi moshi) {
    Class> rawType = Types.getRawType(type);
    if (rawType.isAssignableFrom(Rider.class)) {
    return Rider.adapter(moshi);
    } else if (rawType.isAssignableFrom(City.class)) {
    return City.adapter(moshi);
    } else if (rawType.isAssignableFrom(Vehicle.class)) {
    return Vehicle.adapter(moshi);
    }
    // Etc etc
    return null;
    }
    }
    

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94. astruct Rider
    struct City
    struct Vehicle
    struct Restaurant
    struct Payment
    struct TipAmount
    struct Rating
    //aAnd 6000 more
    

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95. //aAnd 6000 more
    

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96. //aAnd 6000 more
    Rider
    EATS
    Payments
    Driver
    GiftCard
    Pricing
    

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97. Rider
    GiftCard
    Pricing
    Driver
    EATS
    Payments
    

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98. Rider
    - build.gradle
    GiftCard
    - build.gradle
    Pricing
    - build.gradle
    Driver
    - build.gradle
    EATS
    - build.gradle
    Payments
    - build.gradle
    

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99. Rider
    - build.gradle
    GiftCard
    - build.gradle
    Pricing
    - build.gradle
    Driver
    - build.gradle
    EATS
    - build.gradle
    Payments
    - build.gradle
    

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100. Rider
     GiftCard
     Pricing
     Driver
     EATS
     Payments
     

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101. xclass RiderModelFactory
     class GiftCardModelFactory
     class PricingModelFactory
     class DriverModelFactory
     class EATSModelFactory
     class PaymentsModelFactory
     

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102. xclass RiderModelFactory
     

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103. xclass RiderModelFactory
     // -> json
     

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104. xclass RiderModelFactory
     // -> json
     // -> ridermodelfactory-fractory.binx
     

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105. class RiderModelFactory
     // -> json
     // -> ridermodelfactory-fractory.bin
     class MyAppGlobalFactory
     // Delegates to all discovered fractories
     

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106. class RiderModelFactory
     // -> json
     // -> ridermodelfactory-fractory.bin
     class MyAppGlobalFactory
     // Delegates to all discovered fractories
     Fractory
     C
     om
     ing
     Soon™
     

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107. .thrift Thrifty "Jenga" .java
     APT
     AutoValueProcessor
     auto-value-moshi
     fractory
     Pre-build
     Compilation
     *SPI*
     Project Gen *Gradle*
     *Templating*
     *JavaPoet*
     

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108. Tools
     •JavaPoet
     •KotlinPoet
     •Templating
     •SPI
     •Compile Testing
     •Annotation Processing
     (APT)
     •Gradle
     

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109. Pitfalls
     

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110. BLOAT
     

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111. Rider app
     a
     

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112. Rider app
     a b
     10% Dagger
     

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113. Rider app
     a b
     10% Dagger
     c
     25% Models
     

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114. struct Rider {
     1: required string uuid;
     2: required string firstName;
     3: required string lastName;
     4: optional Address address;
     }a
     

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115. struct Rider {
     1: required string uuid;
     2: required string firstName;
     3: required string lastName;
     4: optional Address address;
     }a
     

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116. struct Rider {
     1: required string uuid;
     2: required string firstName;
     3: required string lastName;
     }a
     

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117. struct Rider {
     1: required string uuid;
     2: required string firstName;
     3: required string lastName;
     }a
     service UberService {a
     Rider getRider()
     }b
     

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118. struct Rider {
     1: required string uuid;
     2: required string firstName;
     3: required string lastName;
     }a
     service UberService {a
     Rider getRider()
     }b
     

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119. struct Rider {
     1: required string uuid;
     2: required string firstName;
     3: required string lastName;
     }a
     service UberService {a
     Rider getRider()
     }b
     

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120. Rider app
     a b c
     

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121. Rider app
     a b c $$
     

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122. Fin
     Zac Sweers - Uber
     @pandanomic
     

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