Krate ft. Moshi (Kotlin Budapest Meetup 2021 June)

Krate is a SharedPreferences wrapper library based on Kotlin's delegates. This talk takes you on a journey where you'll learn how the new Moshi-based addon for the library was implemented. We'll touch on type erasure and reflection, testing, debugging, and various advanced Kotlin features along the way.

Resources & more info: https://zsmb.co/talks/krate-ft-moshi/

Transcript

1. zsmb.co
   zsmb13
   A Kotlin library design case study
   ft
   Krate Moshi
   Márton Braun
   

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2. Krate
   AutSoft/Krate
   Moshi
   square/moshi
   

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3. Krate
   AutSoft/Krate
   

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4. Krate
   interface Krate {
   val sharedPreferences: SharedPreferences
   }
   

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5. Krate
   interface Krate {
   val sharedPreferences: SharedPreferences
   }
   abstract class SimpleKrate(context: Context) : Krate {
   override val sharedPreferences =
   PreferenceManager.getDefaultSharedPreferences(context)
   }
   

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6. interface Krate {
   val sharedPreferences: SharedPreferences
   }
   Krate
   class MyKrate(context: Context) : SimpleKrate(context) {
   var onboarded by booleanPref("onboarded")
   var appOpenCount by intPref("appOpenCount")
   var username by stringPref("username")
   }
   abstract class SimpleKrate(context: Context) : Krate {
   override val sharedPreferences =
   PreferenceManager.getDefaultSharedPreferences(context)
   }
   

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7. interface Krate {
   val sharedPreferences: SharedPreferences
   }
   Krate
   myKrate.onboarded = true
   myKrate.appOpenCount++
   myKrate.username = "t1gg3r"
   class MyKrate(context: Context) : SimpleKrate(context) {
   var onboarded by booleanPref("onboarded")
   var appOpenCount by intPref("appOpenCount")
   var username by stringPref("username")
   }
   abstract class SimpleKrate(context: Context) : Krate {
   override val sharedPreferences =
   PreferenceManager.getDefaultSharedPreferences(context)
   }
   

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8. Krate
   myKrate.onboarded = true
   myKrate.appOpenCount++
   myKrate.username = "t1gg3r"
   var onboarded by booleanPref("onboarded")
   var username by stringPref("username")
   abstract class SimpleKrate(context: Context) : Krate {
   override val sharedPreferences =
   PreferenceManager.getDefaultSharedPreferences(context)
   }
   }
   var appOpenCount by intPref("appOpenCount")
   class MyKrate(context: Context) : SimpleKrate(context) {
   

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9. Krate
   class MyKrate(context: Context) : SimpleKrate(context) {
   var appOpenCount by intPref("appOpenCount")
   }
   

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10. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    

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11. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    class IntDelegate(private val key: String)
    

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12. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    class IntDelegate(private val key: String) : ReadWriteProperty {
    }
    

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13. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    class IntDelegate(private val key: String) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
    }
    }
    

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14. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    class IntDelegate(private val key: String) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
    }
    }
    

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15. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount: Int by IntDelegate("appOpenCount")
    }
    class IntDelegate(private val key: String) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
    }
    }
    

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16. Krate
    class IntDelegate(private val key: String) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
    }
    }
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    

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17. Krate
    class IntDelegate(private val key: String) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
    return thisRef.sharedPreferences.getInt(key, 0)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
    thisRef.sharedPreferences.edit().putInt(key, value).apply()
    }
    }
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    

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18. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by IntDelegate("appOpenCount")
    }
    class IntDelegate(private val key: String) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
    return thisRef.sharedPreferences.getInt(key, 0)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
    thisRef.sharedPreferences.edit().putInt(key, value).apply()
    }
    }
    fun Krate.intPref(key: String): ReadWriteProperty {
    return IntDelegate(key)
    }
    

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19. Krate
    class MyKrate(context: Context) : SimpleKrate(context) {
    var appOpenCount by intPref("appOpenCount")
    }
    class IntDelegate(private val key: String) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
    return thisRef.sharedPreferences.getInt(key, 0)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
    thisRef.sharedPreferences.edit().putInt(key, value).apply()
    }
    }
    fun Krate.intPref(key: String): ReadWriteProperty {
    return IntDelegate(key)
    }
    

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20. Krate
    AutSoft/Krate
    

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21. Moshi
    square/moshi
    

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22. Moshi
    

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23. Moshi
    › Gson v3 in everything but name
    

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24. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    Okio
    Retrofit
    OkHttp
    Moshi
    

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25. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    Okio
    Retrofit
    OkHttp
    Moshi
    

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26. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    

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27. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    

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28. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String,
    )
    

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29. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String,
    )
    val moshi = Moshi.Builder().build()
    

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30. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String,
    )
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    

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31. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String,
    )
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    val burger = burgerAdapter.fromJson(
    "{\"name\": \"Cheeseburger\"}"
    )
    

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32. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String,
    )
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    val burger = burgerAdapter.fromJson(
    "{\"name\": \"Cheeseburger\"}"
    )
    Exception in thread "main"
    com.squareup.moshi.JsonDataException:
    Required value 'description' missing at $
    

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33. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String?,
    )
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    val burger = burgerAdapter.fromJson(
    "{\"name\": \"Cheeseburger\"}"
    )
    

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34. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String
    )
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    val burger = burgerAdapter.fromJson(
    "{\"name\": \"Cheeseburger\"}"
    )
    Burger(name=Cheeseburger, description=null)
    ?,
    

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35. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String
    )
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    val burger = burgerAdapter.fromJson(
    "{\"name\": \"Cheeseburger\"}"
    )
    › Default parameter values
    ?,
    

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36. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    val burger = burgerAdapter.fromJson(
    "{\"name\": \"Cheeseburger\"}"
    )
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String
    )
    ,
    = "Yummy!"
    

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37. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    val moshi = Moshi.Builder().build()
    val burgerAdapter =
    moshi.adapter(Burger::class.java)
    val burger = burgerAdapter.fromJson(
    "{\"name\": \"Cheeseburger\"}"
    )
    Burger(name=Cheeseburger, description=Yummy!)
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String
    )
    ,
    = "Yummy!"
    

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38. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    › Codegen, reflection, or both
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String = "Yummy!",
    )
    val moshi = Moshi.Builder().build()
    

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39. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    › Codegen, reflection, or both
    data class Burger(
    val name: String,
    val description: String = "Yummy!",
    )
    val moshi = Moshi.Builder().build()
    

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40. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    › Codegen, reflection, or both
    data class Burger(
    val name: String,
    val description: String = "Yummy!",
    )
    val moshi = Moshi.Builder()
    .add(KotlinJsonAdapterFactory())
    .build()
    

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41. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    › Codegen, reflection, or both
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String = "Yummy!",
    )
    val moshi = Moshi.Builder()
    .add(KotlinJsonAdapterFactory())
    .build()
    

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42. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    › Codegen, reflection, or both
    › Always calls constructors
    @JsonClass(generateAdapter = true)
    data class Burger(
    val name: String,
    val description: String = "Yummy!",
    ) {
    init {
    println("$name coming up...")
    }
    }
    

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43. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    › Always calls constructors
    › Named after Jake’s dog
    › Codegen, reflection, or both
    

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44. Moshi
    › Gson v3 in everything but name
    › Part of the Ok libraries
    › Streaming API
    › Nullable values
    › Default parameter values
    › Always calls constructors
    › Named after Jake’s dog
    › Codegen, reflection, or both
    

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45. Storing complex data
    

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46. DISCLAIMER
    Consider using a database before storing
    data like this in SharedPreferences
    

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47. Gson delegate
    

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48. Gson delegate
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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49. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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50. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    }
    }
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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51. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    }
    }
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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52. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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53. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    java.lang.ClassCastException:
    com.google.gson.internal.LinkedTreeMap
    cannot be cast to
    hu.autsoft.krate.gson.TestModel
    

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54. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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55. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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56. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): Object? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Object?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key)
    }
    

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57. Object
    T
    Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    inline fun ?> {
    return GsonDelegate(key)
    }
    Krate.gsonPref(key: String): ReadWriteProperty

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58. inline fun ?> {
    return GsonDelegate(key)
    }
    Object
    T
    Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    Krate.gsonPref(key: String): ReadWriteProperty

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59. Gson delegate
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, object : TypeToken() {}.type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    inline fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key, object : TypeToken() {}.type)
    }
    

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60. inline fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key, object : TypeToken() {}.type)
    }
    Gson delegate
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    class GsonDelegate(
    private val key: String,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, )
    private val type: Type,
    type
    

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61. Testing Krate
    

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62. Gson delegate tests
    data class TestModel(val x: Int, val y: Double, val z: String)
    

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63. Gson delegate tests
    class GsonTestKrate(context: Context) : SimpleKrate(context) {
    var simpleValue: TestModel? by gsonPref("simpleValue")
    var listOfValues: List? by gsonPref("listOfValues")
    }
    data class TestModel(val x: Int, val y: Double, val z: String)
    

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64. Gson delegate tests
    class GsonTestKrate(context: Context) : SimpleKrate(context) {
    var simpleValue: TestModel? by gsonPref("simpleValue")
    var listOfValues: List? by gsonPref("listOfValues")
    }
    data class TestModel(val x: Int, val y: Double, val z: String)
    val krate = GsonTestKrate(targetContext)
    

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65. Gson delegate tests
    class GsonTestKrate(context: Context) : SimpleKrate(context) {
    var simpleValue: TestModel? by gsonPref("simpleValue")
    var listOfValues: List? by gsonPref("listOfValues")
    }
    @Test
    fun testSimpleValue() {
    val model = TestModel(x = 42, y = 3.141592, z = "shibboleth")
    krate.simpleValue = model
    assertEquals(model, krate.simpleValue)
    }
    data class TestModel(val x: Int, val y: Double, val z: String)
    val krate = GsonTestKrate(targetContext)
    

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66. Gson delegate tests
    class GsonTestKrate(context: Context) : SimpleKrate(context) {
    var simpleValue: TestModel? by gsonPref("simpleValue")
    var listOfValues: List? by gsonPref("listOfValues")
    }
    @Test
    fun testSimpleValue() {
    val model = TestModel(x = 42, y = 3.141592, z = "shibboleth")
    krate.simpleValue = model
    assertEquals(model, krate.simpleValue)
    }
    data class TestModel(val x: Int, val y: Double, val z: String)
    val krate = GsonTestKrate(targetContext)
    

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67. Gson delegate tests
    class GsonTestKrate(context: Context) : SimpleKrate(context) {
    var simpleValue: TestModel? by gsonPref("simpleValue")
    var listOfValues: List? by gsonPref("listOfValues")
    }
    @Test
    fun testListOfValues() {
    val list = listOf(
    TestModel(x = 42, y = 3.141592, z = "shibboleth"),
    TestModel(x = 13, y = 6.283185, z = "signal"),
    )
    krate.listOfValues = list
    assertEquals(list, krate.listOfValues)
    }
    data class TestModel(val x: Int, val y: Double, val z: String)
    val krate = GsonTestKrate(targetContext)
    

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68. Gson delegate tests
    class GsonTestKrate(context: Context) : SimpleKrate(context) {
    var simpleValue: TestModel? by gsonPref("simpleValue")
    var listOfValues: List? by gsonPref("listOfValues")
    }
    @Test
    fun testListOfValues() {
    val list = listOf(
    TestModel(x = 42, y = 3.141592, z = "shibboleth"),
    TestModel(x = 13, y = 6.283185, z = "signal"),
    )
    krate.listOfValues = list
    assertEquals(list, krate.listOfValues)
    }
    data class TestModel(val x: Int, val y: Double, val z: String)
    val krate = GsonTestKrate(targetContext)
    

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69. ft
    Krate Moshi
    

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70. class GsonDelegate(
    private val key: String,
    private val type: Type,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val gson = Gson()
    val string = thisRef.sharedPreferences.getString(key, null)
    return gson.fromJson(string, type)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    inline fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key, object : TypeToken() {}.type)
    }
    Moshi delegate
    

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71. inline fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key, object : TypeToken() {}.type)
    }
    Moshi delegate
    gson Gson()
    =
    .fromJson(string )
    , type
    gson
    class MoshiDelegate(
    private val key: String,
    private val type: Type,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val
    val string = thisRef.sharedPreferences.getString(key, null)
    return
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    

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72. inline fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key, object : TypeToken() {}.type)
    }
    Moshi delegate
    moshi.adapter(type)
    =
    adapter
    .fromJson(string)
    adapter
    class MoshiDelegate(
    private val key: String,
    private val type: Type,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val
    val string = thisRef.sharedPreferences.getString(key, null)
    return
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val gson = Gson()
    thisRef.sharedPreferences.edit()
    .putString(key, gson.toJson(value))
    .apply()
    }
    }
    

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73. class MoshiDelegate(
    private val key: String,
    private val type: Type,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val adapter = moshi.adapter(type)
    val string = thisRef.sharedPreferences.getString(key, null)
    return adapter.fromJson(string)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val adapter = moshi.adapter(type)
    thisRef.sharedPreferences.edit()
    .putString(key, adapter.toJson(value))
    .apply()
    }
    }
    inline fun Krate.gsonPref(key: String): ReadWriteProperty {
    return GsonDelegate(key, object : TypeToken() {}.type)
    }
    Moshi delegate
    

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74. class MoshiDelegate(
    private val key: String,
    private val type: Type,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val adapter = moshi.adapter(type)
    val string = thisRef.sharedPreferences.getString(key, null)
    return adapter.fromJson(string)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val adapter = moshi.adapter(type)
    thisRef.sharedPreferences.edit()
    .putString(key, adapter.toJson(value))
    .apply()
    }
    }
    inline fun Krate.moshiPref(key: String): ReadWriteProperty {
    return MoshiDelegate(key, object : TypeToken() {}.type)
    }
    Moshi delegate
    

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75. class MoshiDelegate(
    private val key: String,
    private val type: Type,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val adapter = moshi.adapter(type)
    val string = thisRef.sharedPreferences.getString(key, null)
    return adapter.fromJson(string)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val adapter = moshi.adapter(type)
    thisRef.sharedPreferences.edit()
    .putString(key, adapter.toJson(value))
    .apply()
    }
    }
    inline fun Krate.moshiPref(key: String): ReadWriteProperty {
    return MoshiDelegate(key, object : TypeToken() {}.type)
    }
    Moshi delegate
    

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76. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
    return MoshiDelegate(key,
    }
    class MoshiDelegate(
    private val key: String,
    private val type: Type,
    ) : ReadWriteProperty {
    override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
    val adapter = moshi.adapter(type)
    val string = thisRef.sharedPreferences.getString(key, null)
    return adapter.fromJson(string)
    }
    override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: T?) {
    val adapter = moshi.adapter(type)
    thisRef.sharedPreferences.edit()
    .putString(key, adapter.toJson(value))
    .apply()
    }
    }
    Moshi delegate
    ???)
    

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77. Class
    

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78. java.lang.Class
    

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79. java.lang.Class
    classes and interfaces in a running Java application
    

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80. java.lang.Class
    classes and interfaces in a running Java application
    Class c1 = object.getClass();
    

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81. java.lang.Class
    classes and interfaces in a running Java application
    Class c1 = object.getClass(); any.javaClass // Kotlin
    

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82. java.lang.Class
    classes and interfaces in a running Java application
    Class c1 = object.getClass();
    Class c2 = String.class;
    any.javaClass // Kotlin
    

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83. java.lang.Class
    classes and interfaces in a running Java application
    Class c1 = object.getClass();
    Class c2 = String.class;
    any.javaClass
    "hello world".getClass(); // class java.lang.String
    new ArrayList().getClass(); // class java.util.ArrayList
    new Serializable() {}.getClass(); // class com.example.Main$1
    // Kotlin
    

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84. java.lang.Class
    classes and interfaces in a running Java application
    Class c1 = object.getClass();
    Class c2 = String.class;
    any.javaClass
    c.getName();
    c.getSimpleName();
    c.getCanonicalName();
    c.getTypeName();
    // Kotlin
    [I
    int[]
    int[]
    int[]
    java.lang.String
    String
    java.lang.String
    java.lang.String
    com.example.Main$1
    null
    com.example.Main$1
    

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85. java.lang.Class
    classes and interfaces in a running Java application
    Class c1 = object.getClass();
    Class c2 = String.class;
    any.javaClass
    c.getName();
    c.getSimpleName();
    c.getCanonicalName();
    c.getTypeName();
    Annotation[] annotations = c.getAnnotations();
    Class[] interfaces = c.getInterfaces();
    Constructor[] constructors = c.getConstructors();
    Field[] fields = c.getFields();
    Method[] methods = c.getMethods();
    // Kotlin
    [I
    int[]
    int[]
    int[]
    java.lang.String
    String
    java.lang.String
    java.lang.String
    com.example.Main$1
    null
    com.example.Main$1
    

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86. java.lang.reflect.Type
    

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87. java.lang.reflect.Type
    all types in the Java programming language
    - raw types
    - parameterized types
    - array types
    - type variables
    - primitive types
    

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88. java.lang.reflect.Type
    all types in the Java programming language
    - raw types
    - parameterized types
    - array types
    - type variables
    - primitive types
    String getTypeName();
    

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89. java.lang.reflect.Type
    all types in the Java programming language
    - raw types
    - parameterized types
    - array types
    - type variables
    - primitive types
    Class
    String getTypeName();
    

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90. java.lang.reflect.Type
    all types in the Java programming language
    - raw types
    - parameterized types
    - array types
    - type variables
    - primitive types
    Class ParameterizedType
    Type getRawType();
    Type[] getActualTypeArguments();
    String getTypeName();
    

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91. Class Type
    No generics Supports generics
    Java reflection
    

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92. Class Type
    No generics Supports generics
    Java reflection
    Kotlin reflection
    

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93. Class Type
    No generics Supports generics
    Java reflection
    Kotlin reflection
    KClass
    

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94. kotlin.reflect.KClass
    

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95. kotlin.reflect.KClass
    val k1: KClass<*> = any::class
    val k2: KClass<*> = String::class
    

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96. kotlin.reflect.KClass
    val simpleName: String?
    val qualifiedName: String?
    val members: Collection>
    val constructors: Collection>
    val nestedClasses: Collection>
    val typeParameters: List
    val supertypes: List
    val sealedSubclasses: List>
    val visibility: KVisibility?
    val k1: KClass<*> = any::class
    val k2: KClass<*> = String::class
    

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97. kotlin.reflect.KClass
    val k1: KClass<*> = any::class
    val k2: KClass<*> = String::class
    val isFinal: Boolean
    val isOpen: Boolean
    val isAbstract: Boolean
    val isSealed: Boolean
    val isData: Boolean
    val isInner: Boolean
    val isCompanion: Boolean
    val isFun: Boolean
    

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98. val c: Class<*> = String::class.java
    kotlin.reflect.KClass
    val k1: KClass<*> = any::class
    val k2: KClass<*> = String::class
    

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99. val c: Class<*> = String::class.java
    kotlin.reflect.
    val k1: KClass<*> = any::class
    val k2: KClass<*> = String::class
    String.class // Java
    // Kotlin
    KClass
    

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100. Class Type
     No generics Supports generics
     Java reflection
     Kotlin reflection
     KClass
     

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101. Class Type
     No generics Supports generics
     Java reflection
     Kotlin reflection
     KClass KType
     ParameterizedType
     

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102. Class Type
     No generics Supports generics
     Java reflection
     Kotlin reflection
     KClass KType
     ParameterizedType
     

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103. Class Type
     No generics Supports generics
     Java reflection
     Kotlin reflection
     KClass KType
     rawType
     actualTypeArguments
     ParameterizedType
     

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104. Class Type
     No generics Supports generics
     Java reflection
     Kotlin reflection
     KClass KType
     rawType
     actualTypeArguments
     ParameterizedType
     classifier
     arguments
     

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105. rawType
     actualTypeArguments
     ParameterizedType
     classifier
     arguments
     isMarkedNullable
     Class Type
     No generics Supports generics
     Java reflection
     Kotlin reflection
     KClass KType
     

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106. rawType
     actualTypeArguments
     ParameterizedType
     classifier
     arguments
     Class Type
     No generics Supports generics
     Java reflection
     Kotlin reflection
     KClass KType
     

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107. Looking for a Type
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, ???)
     }
     class MoshiDelegate(
     private val key: String,
     private val type: Type,
     ) : ReadWriteProperty {
     ...
     }
     

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108. Looking for a Type
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     class MoshiDelegate(
     private val key: String,
     private val type: Type,
     ) : ReadWriteProperty {
     ...
     }
     

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109. Looking for a Type
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     class MoshiDelegate(
     private val key: String,
     private val type: Type,
     ) : ReadWriteProperty {
     ...
     }
     

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110. Moshi delegate tests
     class GsonTestKrate(context: Context) : SimpleKrate(context) {
     var simpleValue: TestModel? by gsonPref("simpleValue")
     var listOfValues: List? by gsonPref("listOfValues")
     }
     @Test
     fun testSimpleValue() {
     val model = TestModel(x = 42, y = 3.141592, z = "shibboleth")
     krate.simpleValue = model
     assertEquals(model, krate.simpleValue)
     }
     data class TestModel(val x: Int, val y: Double, val z: String)
     val krate = GsonTestKrate(targetContext)
     

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111. Moshi delegate tests
     class MoshiTestKrate(context: Context) : SimpleKrate(context) {
     var simpleValue: TestModel? by moshiPref("simpleValue")
     var listOfValues: List? by moshiPref("listOfValues")
     }
     @Test
     fun testSimpleValue() {
     val model = TestModel(x = 42, y = 3.141592, z = "shibboleth")
     krate.simpleValue = model
     assertEquals(model, krate.simpleValue)
     }
     data class TestModel(val x: Int, val y: Double, val z: String)
     val krate = GsonTestKrate(targetContext)
     

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112. Moshi delegate tests
     class MoshiTestKrate(context: Context) : SimpleKrate(context) {
     var simpleValue: TestModel? by moshiPref("simpleValue")
     var listOfValues: List? by moshiPref("listOfValues")
     }
     @Test
     fun testSimpleValue() {
     val model = TestModel(x = 42, y = 3.141592, z = "shibboleth")
     krate.simpleValue = model
     assertEquals(model, krate.simpleValue)
     }
     data class TestModel(val x: Int, val y: Double, val z: String)
     val krate = MoshiTestKrate(targetContext)
     

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113. Moshi delegate tests
     class MoshiTestKrate(context: Context) : SimpleKrate(context) {
     var simpleValue: TestModel? by moshiPref("simpleValue")
     var listOfValues: List? by moshiPref("listOfValues")
     }
     @Test
     fun testSimpleValue() {
     val model = TestModel(x = 42, y = 3.141592, z = "shibboleth")
     krate.simpleValue = model
     assertEquals(model, krate.simpleValue)
     }
     data class TestModel(val x: Int, val y: Double, val z: String)
     val krate = MoshiTestKrate(targetContext)
     

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114. Moshi delegate tests
     class MoshiTestKrate(context: Context) : SimpleKrate(context) {
     var simpleValue: TestModel? by moshiPref("simpleValue")
     var listOfValues: List? by moshiPref("listOfValues")
     }
     @Test
     fun testListOfValues() {
     val list = listOf(
     TestModel(x = 42, y = 3.141592, z = "shibboleth"),
     TestModel(x = 13, y = 6.283185, z = "signal"),
     )
     krate.listOfValues = list
     assertEquals(list, krate.listOfValues)
     }
     data class TestModel(val x: Int, val y: Double, val z: String)
     val krate = MoshiTestKrate(targetContext)
     

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115. Moshi delegate tests
     class MoshiTestKrate(context: Context) : SimpleKrate(context) {
     var simpleValue: TestModel? by moshiPref("simpleValue")
     var listOfValues: List? by moshiPref("listOfValues")
     }
     @Test
     fun testListOfValues() {
     val list = listOf(
     TestModel(x = 42, y = 3.141592, z = "shibboleth"),
     TestModel(x = 13, y = 6.283185, z = "signal"),
     )
     krate.listOfValues = list
     assertEquals(list, krate.listOfValues)
     }
     data class TestModel(val x: Int, val y: Double, val z: String)
     val krate = MoshiTestKrate(targetContext)
     

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116. class MoshiTestKrate(context: Context) : SimpleKrate(context) {
     var simpleValue: TestModel? by moshiPref("simpleValue")
     var listOfValues: List? by moshiPref("listOfValues")
     }
     @Test
     fun testListOfValues() {
     val list = listOf(
     TestModel(x = 42, y = 3.141592, z = "shibboleth"),
     TestModel(x = 13, y = 6.283185, z = "signal"),
     )
     krate.listOfValues = list
     assertEquals(list, krate.listOfValues)
     }
     data class TestModel(val x: Int, val y: Double, val z: String)
     val krate = MoshiTestKrate(targetContext)
     Moshi delegate tests
     java.lang.AssertionError:
     Expected :[
     TestModel(x=42, y=3.141592, z=shibboleth),
     TestModel(x=13, y=6.283185, z=signal)
     ]
     Actual :[
     {x=42.0, y=3.141592, z=shibboleth},
     {x=13.0, y=6.283185, z=signal}
     ]
     

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117. java.lang.AssertionError:
     Expected :[
     TestModel(x=42, y=3.141592, z=shibboleth),
     TestModel(x=13, y=6.283185, z=signal)
     ]
     Actual :[
     {x=42.0, y=3.141592, z=shibboleth},
     {x=13.0, y=6.283185, z=signal}
     ]
     

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118. Actual :[
     {x=42.0, y=3.141592, z=shibboleth},
     {x=13.0, y=6.283185, z=signal}
     ]
     

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119. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Moshi delegate tests
     

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120. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Moshi delegate tests
     

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121. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Moshi delegate tests
     

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122. var simpleValue by moshiPref("simpleValue")
     var listOfValues by moshiPref>("listOfValues")
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Moshi delegate tests
     

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123. var simpleValue by moshiPref("simpleValue")
     var listOfValues by moshiPref>("listOfValues")
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     class hu.autsoft.krate.moshi.TestModel
     Moshi delegate tests
     

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124. class hu.autsoft.krate.moshi.TestModel
     interface java.util.List
     var simpleValue by moshiPref("simpleValue")
     var listOfValues by moshiPref>("listOfValues")
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Moshi delegate tests
     

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125. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Looking for a Type
     

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126. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Types.newParameterizedType(List::class.java, TestModel::class.java)
     Looking for a Type
     

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127. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, T::class.java)
     }
     Types.newParameterizedType(List::class.java, TestModel::class.java)
     java.util.List
     Looking for a Type
     

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128. inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(
     key,
     Types.newParameterizedType(T::class.java, ???::class.java)
     )
     }
     Types.newParameterizedType(List::class.java, TestModel::class.java)
     java.util.List
     Looking for a Type
     

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129. Looking for a Type
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key,
     }
     )
     ???
     

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130. Looking for a Type
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, object : TypeToken() {}.type)
     }
     

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131. TypeToken object : TypeToken() {}.type
     

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132. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     

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133. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     

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134. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     

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135. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     

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136. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     getGenericSuperclass();
     

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137. getGenericSuperclass();
     * ...
     */
     public Type
     /**
     * Returns the Type representing the direct superclass of the entity
     * represented by this Class.
     *
     

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138. * If the superclass is a parameterized type, the Type object returned must
     * accurately reflect the actual type parameters used in the source code.
     *
     getGenericSuperclass();
     * ...
     */
     public Type
     /**
     * Returns the Type representing the direct superclass of the entity
     * represented by this Class.
     *
     

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139. * Non-parameterized -> Class
     * Parameterized -> ParameterizedType
     * If the superclass is a parameterized type, the Type object returned must
     * accurately reflect the actual type parameters used in the source code.
     *
     getGenericSuperclass();
     * ...
     */
     public Type
     /**
     * Returns the Type representing the direct superclass of the entity
     * represented by this Class.
     *
     

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140. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     getGenericSuperclass();
     

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141. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     

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142. TypeToken
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return canonicalize(parameterized.getActualTypeArguments()[0]);
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     }
     object : TypeToken() {}.type
     

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143. TypeToken object : TypeToken() {}.type
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     parameterized.getActualTypeArguments()[0]
     canonicalize( );
     return
     }
     }
     /**
     * Returns a type that is functionally equal but not necessarily equal
     * according to Object.equals().
     */
     public static Type canonicalize(Type type) { ... }
     

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144. parameterized.getActualTypeArguments()[0]
     TypeToken object : TypeToken() {}.type
     ;
     public class TypeToken {
     final Type type = getSuperclassTypeParameter(getClass());
     protected TypeToken() {}
     static Type getSuperclassTypeParameter(Class> subclass) {
     Type superclass = subclass.getGenericSuperclass();
     if (superclass instanceof Class) {
     throw new RuntimeException("Missing type parameter.");
     }
     ParameterizedType parameterized = (ParameterizedType) superclass;
     return
     }
     }
     

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145. open constructor
     val
     fun : * :
     val
     is <*>
     val as
     getGenericSuperclass()
     getActualTypeArguments()
     TypeToken object : TypeToken() {}.type
     subclass
     getSuperclassTypeParameter Class< >) Type
     (
     type = getSuperclassTypeParameter( )
     class TypeToken
     {
     {
     {
     }
     }
     }
     return parameterized.
     parameterized =
     ()
     protected
     javaClass
     if (superclass Class
     superclass = subclass.
     )
     superclass ParameterizedType
     RuntimeException("Missing type parameter.")
     throw
     [0]
     actualTypeArguments
     genericSuperclass
     

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146. : Type requireNotNull token::class.java
     if (superclass is Class<*>) {
     throw RuntimeException("Missing type parameter.")
     }
     val parameterized = superclass as ParameterizedType
     return parameterized.actualTypeArguments[0]
     }
     TypeToken object : TypeToken() {}.type
     abstract
     ): Type {
     .genericSuperclass
     ( )
     class TypeToken
     val token = object : TypeToken() {}
     inline makeType
     =
     val superclass
     (
     fun
     

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147. TypeToken makeType()
     : Type requireNotNull token::class.java
     if (superclass is Class<*>) {
     throw RuntimeException("Missing type parameter.")
     }
     val parameterized = superclass as ParameterizedType
     return parameterized.actualTypeArguments[0]
     }
     abstract
     ): Type {
     .genericSuperclass
     ( )
     class TypeToken
     val token = object : TypeToken() {}
     inline makeType
     =
     val superclass
     (
     fun
     

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148. TypeToken
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, )
     }
     makeType()
     : Type requireNotNull token::class.java
     if (superclass is Class<*>) {
     throw RuntimeException("Missing type parameter.")
     }
     val parameterized = superclass as ParameterizedType
     return parameterized.actualTypeArguments[0]
     }
     abstract
     ): Type {
     .genericSuperclass
     ( )
     class TypeToken
     val token = object : TypeToken() {}
     inline makeType
     =
     val superclass
     (
     fun
     

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149. TypeToken
     

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150. typeOf
     inline fun makeType(): Type
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, makeType())
     }
     

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151. typeOf
     inline fun makeType(): Type
     /**
     * Returns a runtime representation of the given
     * reified type [T] as an instance of [KType].
     */
     inline fun typeOf(): KType
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, makeType())
     }
     

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152. typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf())
     }
     /**
     * Returns a runtime representation of the given
     * reified type [T] as an instance of [KType].
     */
     inline fun typeOf(): KType
     

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153. typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf())
     }
     /**
     * Returns a runtime representation of the given
     * reified type [T] as an instance of [KType].
     */
     inline fun typeOf(): KType
     

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154. typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf())
     }
     /**
     * Returns a runtime representation of the given
     * reified type [T] as an instance of [KType].
     */
     inline fun typeOf(): KType
     /**
     * Returns a Java [Type] instance corresponding
     * to the given Kotlin type.
     */
     val KType.javaType: Type
     

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155. typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf().javaType)
     }
     /**
     * Returns a runtime representation of the given
     * reified type [T] as an instance of [KType].
     */
     inline fun typeOf(): KType
     /**
     * Returns a Java [Type] instance corresponding
     * to the given Kotlin type.
     */
     val KType.javaType: Type
     

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156. typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf().javaType)
     }
     /**
     * Returns a runtime representation of the given
     * reified type [T] as an instance of [KType].
     */
     inline fun typeOf(): KType
     /**
     * Returns a Java [Type] instance corresponding
     * to the given Kotlin type.
     */
     val KType.javaType: Type
     NotImplementedError:
     Java type is not yet supported for types
     created with createType
     

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157. typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf().javaType)
     }
     /**
     * Returns a runtime representation of the given
     * reified type [T] as an instance of [KType].
     */
     /**
     * Returns a Java [Type] instance corresponding
     * to the given Kotlin type.
     */
     val KType.javaType: Type
     inline fun typeOf(): KType
     NotImplementedError:
     Java type is not yet supported for types
     created with createType
     

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158. makeType
     typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf().javaType)
     }
     inline fun typeOf(): KType
     val KType.javaType: Type
     fun KClassifier.createType(...): KType {
     ...
     return KTypeImpl(kotlinType) {
     TODO("Java type is not yet supported for types created with createType")
     }
     }
     

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159. typeOf
     inline fun typeOf(): KType
     val KType.javaType: Type
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, makeType())
     }
     

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160. typeOf
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf().javaType)
     }
     inline fun typeOf(): KType
     val KType.javaType: Type
     

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161. typeOf
     @OptIn(ExperimentalStdlibApi::class)
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf().javaType)
     }
     inline fun typeOf(): KType
     val KType.javaType: Type
     

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162. typeOf
     @OptIn(ExperimentalStdlibApi::class)
     inline fun Krate.moshiPref(key: String): ReadWriteProperty {
     return MoshiDelegate(key, typeOf().javaType)
     }
     inline fun typeOf(): KType
     val KType.javaType: Type
     

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163. Resources
     

     View Slide

164. • Krate
      https://github.com/AutSoft/Krate
     • Moshi
      https://github.com/square/moshi
     Resources
     

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165. • Krate
      https://github.com/AutSoft/Krate
     • Moshi
      https://github.com/square/moshi
     • Delightful Delegate Design
      https://www.droidcon.com/media-detail?video=481186381
     • Say “hi” to Moshi!
      https://www.youtube.com/watch?v=qadYVYc-8mc
     Resources
     

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166. • Krate
      https://github.com/AutSoft/Krate
     • Moshi
      https://github.com/square/moshi
     • Delightful Delegate Design
      https://www.droidcon.com/media-detail?video=481186381
     • Say “hi” to Moshi!
      https://www.youtube.com/watch?v=qadYVYc-8mc
     • Library design articles
      https://zsmb.co/maintaining-compatibility-in-kotlin-libraries/
      https://zsmb.co/mastering-api-visibility-in-kotlin/
      https://zsmb.co/talks/how-to-build-awesome-android-libraries/
     Resources
     

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167. zsmb13
     zsmb.co/talks
     

     View Slide

168. ft
     Krate Moshi
     A Kotlin library design case study
     zsmb.co/talks
     zsmb13
     Márton Braun
     › Krate is great
     › Moshi is awesome
     › Type erasure is evil
     › Tests are your friend
     

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