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Delightful Delegate Design
Braun Márton Szabolcs
zsmb.co zsmb13
[email protected]
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No content
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val oneToOne: Pair = 1 to "one"
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with(user) {
println(name)
}
val oneToOne: Pair = 1 to "one"
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val reader = BufferedReader(...)
reader.use {
val line = it.readLine()
// ...
}
with(user) {
println(name)
}
val oneToOne: Pair = 1 to "one"
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val pi: Double by lazy {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
}
println(pi)
println(pi)
val reader = BufferedReader(...)
reader.use {
val line = it.readLine()
// ...
}
with(user) {
println(name)
}
val oneToOne: Pair = 1 to "one"
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val pi: Double by
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
println(pi)
println(pi)
lazy
}
{
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val pi: Double by
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
println(pi)
println(pi)
lazy
}
{
https://forums.swift.org/t/pitch-property-delegates/21895
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val pi: Double by
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
println(pi)
println(pi)
LazyDelegate(
})
{
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class Constants {
private var pi_: Double? = null
val pi: Double
get() {
if (pi_ == null) {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
pi_ = sqrt(sum * 6.0)
}
return pi_!!
}
private var e_: Double? = null
val e: Double
get() {
if (e_ == null) {
val sum = (0..20).sumByDouble { 1.0 / (1..it).fold(1, { a, x -> a * x }) }
e_ = sum
}
return e_!!
}
}
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class Constants {
private var pi_: Double? = null
val pi: Double
get() {
if (pi_ == null) {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
pi_ = sqrt(sum * 6.0)
}
return pi_!!
}
private var e_: Double? = null
val e: Double
get() {
if (e_ == null) {
val sum = (0..20).sumByDouble { 1.0 / (1..it).fold(1, { a, x -> a * x }) }
e_ = sum
}
return e_!!
}
}
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class Constants {
private var pi_: Double? = null
val pi: Double
get() {
if (pi_ == null) {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
pi_ = sqrt(sum * 6.0)
}
return pi_!!
}
private var e_: Double? = null
val e: Double
get() {
if (e_ == null) {
val sum = (0..20).sumByDouble { 1.0 / (1..it).fold(1, { a, x -> a * x }) }
e_ = sum
}
return e_!!
}
}
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class Constants {
private var pi_: Double? = null
val pi: Double
get() {
if (pi_ == null) {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
pi_ = sqrt(sum * 6.0)
}
return pi_!!
}
private var e_: Double? = null
val e: Double
get() {
if (e_ == null) {
val sum = (0..20).sumByDouble { 1.0 / (1..it).fold(1, { a, x -> a * x }) }
e_ = sum
}
return e_!!
}
}
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val pi: Double by LazyDelegate({
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
})
println(pi)
println(pi)
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val pi: Double by LazyDelegate({
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
})
println(pi)
println(pi)
class LazyDelegate(private val initializer: () -> T) {
}
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val pi: Double by LazyDelegate({
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
})
println(pi)
println(pi)
class LazyDelegate(private val initializer: () -> T) {
}
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
}
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val pi: Double by LazyDelegate({
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
})
println(pi)
println(pi)
class LazyDelegate(private val initializer: () -> T) {
}
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
}
private var value: T? = null
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class LazyDelegate(private val initializer: () -> T) {
}
val pi: Double by LazyDelegate({
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
})
println(pi)
println(pi)
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
}
private var value: T? = null
if (value == null) { value = initializer() }
return value!!
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val pi: Double by LazyDelegate({
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
})
println(pi) // 12597400 ns
println(pi) // 72100 ns
class LazyDelegate(private val initializer: () -> T) {
private var value: T? = null
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
if (value == null) { value = initializer() }
return value!!
}
}
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val pi: Double by LazyDelegate({
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
})
println(pi) // 12597400 ns
println(pi) // 72100 ns
class LazyDelegate(private val initializer: () -> T) {
private var value: T? = null
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
if (value == null) { value = initializer() }
return value!!
}
}
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val pi: Double by LazyDelegate {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
}
println(pi) // 12597400 ns
println(pi) // 72100 ns
class LazyDelegate(private val initializer: () -> T) {
private var value: T? = null
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
if (value == null) { value = initializer() }
return value!!
}
}
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val pi: Double by lazy {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
}
println(pi) // 12597400 ns
println(pi) // 72100 ns
class LazyDelegate(private val initializer: () -> T) {
private var value: T? = null
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
if (value == null) { value = initializer() }
return value!!
}
}
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val pi: Double by lazy {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
}
println(pi) // 12597400 ns
println(pi) // 72100 ns
class lazy(private val initializer: () -> T) {
private var value: T? = null
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
if (value == null) { value = initializer() }
return value!!
}
}
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val pi: Double by lazy {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
}
println(pi) // 12597400 ns
println(pi) // 72100 ns
class LazyDelegate(private val initializer: () -> T) {
private var value: T? = null
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
if (value == null) { value = initializer() }
return value!!
}
}
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fun lazy(initializer: () -> T) = LazyDelegate(initializer)
class LazyDelegate(private val initializer: () -> T) {
private var value: T? = null
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
if (value == null) { value = initializer() }
return value!!
}
}
val pi: Double by lazy {
val sum = (1..50_000).sumByDouble { 1.0 / (it * it) }
sqrt(sum * 6.0)
}
println(pi) // 12597400 ns
println(pi) // 72100 ns
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https://github.com/AutSoft/Krate
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krate
interface Krate {
val sharedPreferences: SharedPreferences
}
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krate
interface Krate {
val sharedPreferences: SharedPreferences
}
abstract class SimpleKrate(context: Context) : Krate {
override val sharedPreferences =
PreferenceManager.getDefaultSharedPreferences(context)
}
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krate
interface Krate {
val sharedPreferences: SharedPreferences
}
abstract class SimpleKrate(context: Context) : Krate {
override val sharedPreferences =
PreferenceManager.getDefaultSharedPreferences(context)
}
app
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app
krate
class MyKrate(context: Context) : SimpleKrate(context) {
var onboarded by booleanPref("onboarded")
var appOpenCount by intPref("appOpenCount")
var username by stringPref("username")
}
myKrate.onboarded = true
myKrate.appOpenCount++
myKrate.username = "t1gg3r"
interface Krate {
val sharedPreferences: SharedPreferences
}
abstract class SimpleKrate(context: Context) : Krate {
override val sharedPreferences =
PreferenceManager.getDefaultSharedPreferences(context)
}
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app
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
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krate
app
interface Krate {
val sharedPreferences: SharedPreferences
}
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krate
app
interface Krate {
val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
}
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krate
app
interface Krate {
val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by ???
}
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app
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by ???
}
println(myKrate.score) // 0
myKrate.score = 34
println(myKrate.score) // 34
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app
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by ???
}
println(myKrate.score) // 0
myKrate.score = 34
println(myKrate.score) // 34
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
}
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krate
app
interface Krate {
val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by ???
}
println(myKrate.score) // 0
myKrate.score = 34
println(myKrate.score) // 34
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
}
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app
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
}
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by ???
}
println(myKrate.score) // 0
myKrate.score = 34
println(myKrate.score) // 34
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app
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by ???
}
println(myKrate.score) // 0
myKrate.score = 34
println(myKrate.score) // 34
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app
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by ???
}
println(myKrate.score) // 0
myKrate.score = 34
println(myKrate.score) // 34
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by IntDelegate(sharedPreferences, "score")
}
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
}
println(myKrate.score) // 0
myKrate.score = 34
println(myKrate.score) // 34
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app
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by IntDelegate(sharedPreferences, "score")
}
fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
interface Krate {
val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
override operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
override operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
override operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
override operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
override operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
override operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
override operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
override operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
private val key: String
) : ReadWriteProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): Int {
return sharedPreferences.getInt(key, 0)
}
override operator fun setValue(thisRef: Krate, property: KProperty<*>, value: Int) {
sharedPreferences.edit().putInt(key, value).apply()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class IntDelegate(
private val sharedPreferences: SharedPreferences,
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()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(sharedPreferences, key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal 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()
}
}
public fun Krate.intPref(key: String): IntDelegate {
return IntDelegate(key)
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
var score: Int by intPref("score")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal 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()
}
}
public fun Krate.intPref(key: String): ReadWriteProperty {
return IntDelegate(key)
}
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app
krate
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
var users: List? by ???
}
myKrate.users = listOf(User("William"), User("Virginia"))
println(myKrate.users)
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
va users: List? by gsonPref("users")
}
myKrate.users = listOf(User("William"), User("Virginia"))
println(myKrate.users)
r
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
va users: List? by gsonPref("users")
}
myKrate.users = listOf(User("William"), User("Virginia"))
println(myKrate.users)
l
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app
myKrate.users = listOf(User("William"), User("Virginia"))
println(myKrate.users)
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by gsonPref("users")
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
internal class GsonDelegate(
private val key: String
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string, object : TypeToken() {}.type)
}
}
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by gsonPref("users")
}
internal class GsonDelegate(
private val key: String
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string, object : TypeToken() {}.type)
}
}
public fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key)
}
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by gsonPref("users")
}
internal class GsonDelegate(
private val key: String
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): Object? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string, object : TypeToken() {}.type)
}
}
public fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key)
}
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by gsonPref("users")
}
internal class GsonDelegate(
private val key: String
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string, object : TypeToken() {}.type)
}
}
public fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key)
}
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by gsonPref("users")
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key)
}
object : TypeToken() {}.type)
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
internal class GsonDelegate(
private val key: String
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app
gsonPref("users")
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
object : TypeToken() {}.type)
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
internal class GsonDelegate(
private val key: String
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app
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
}
gsonPref("users")
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
,
private val type: Type
type)
internal class GsonDelegate(
private val key: String
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
GsonDelegate(key, object : TypeToken() {}.type)
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
} gsonPref("users")
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
,
private val type: Type
type)
internal class GsonDelegate(
private val key: String
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app
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
}
GsonDelegate( , object : TypeToken< >() {}.type)
"users"
gsonPref("users")
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
,
private val type: Type
type)
internal class GsonDelegate(
private val key: String
T
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app
GsonDelegate( , object : TypeToken< >() {}.type)
"users" List
gsonPref("users")
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
}
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
,
private val type: Type
type)
internal class GsonDelegate(
private val key: String
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app
gsonPref("users")
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
}
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
,
private val type: Type
type)
internal class GsonDelegate(
private val key: String
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app
gsonPref("users")
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
,
private val type: Type
type)
internal class GsonDelegate(
private val key: String
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
}
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app
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by
} gsonPref("users")
GsonDelegate(...)
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string,
}
}
,
private val type: Type
type)
internal class GsonDelegate(
private val key: String
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app
krate
public interface Krate {
public val sharedPreferences: SharedPreferences
}
class MyKrate(context: Context) : SimpleKrate(context) {
val users: List? by gsonPref("users")
}
@PublishedApi
internal class GsonDelegate(
private val key: String,
private val type: Type
) : ReadOnlyProperty {
override operator fun getValue(thisRef: Krate, property: KProperty<*>): T? {
val string = thisRef.sharedPreferences.getString(key, null)
return Gson().fromJson(string, type)
}
}
public inline fun Krate.gsonPref(
key: String
): ReadOnlyProperty {
return GsonDelegate(key, object : TypeToken() {}.type)
}
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https://zsmb.co/maintaining-compatibility-in-kotlin-libraries/
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Krate*
class MyKrate(context: Context) : SimpleKrate(context) {
var onboarded
var appOpenCount
var username
}
myKrate.onboarded = true
myKrate.appOpenCount++
println(myKrate.username)
by booleanPref("onboarded"
by intPref("appOpenCount"
by stringPref("username"
)
)
)
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class MyKrate(context: Context) : SimpleKrate(context) {
var onboarded: Boolean by booleanPref("onboarded", defaultValue = false)
var appOpenCount: Int by intPref("appOpenCount", defaultValue = 0)
var username: String? by stringPref("username")
}
Krate*
myKrate.onboarded = true
myKrate.appOpenCount++
println(myKrate.username)
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class MyKrate(context: Context) : SimpleKrate(context) {
// non-nullable, has default value
var onboarded: Boolean by booleanPref("onboarded", defaultValue = false)
var appOpenCount: Int by intPref("appOpenCount", defaultValue = 0)
// nullable, null by default
var username: String? by stringPref("username")
}
Krate*
myKrate.onboarded = true
myKrate.appOpenCount++
println(myKrate.username)
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class MyKrate(context: Context) : SimpleKrate(context {
// non-nullable, has default value
var onboarded: Boolean
by booleanPref("onboarded", defaultValue = false)
var appOpenCount: Int
by intPref("appOpenCount", defaultValue = 0)
// nullable, null by default
var username: String?
by stringPref("username")
}
Krate*
myKrate.onboarded = true
myKrate.appOpenCount++
println(myKrate.username)
)
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Krate*
myKrate.onboarded = true
myKrate.appOpenCount++
println(myKrate.username)
class MyKrate(context: Context) : SimpleKrate(context , AppSettings {
// non-nullable, has default value
override var onboarded: Boolean
by booleanPref("onboarded", defaultValue = false)
override var appOpenCount: Int
by intPref("appOpenCount", defaultValue = 0)
// nullable, null by default
override var username: String?
by stringPref("username")
}
)
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class MyKrate @Inject constructor(context: Context)
// non-nullable, has default value
override var onboarded: Boolean
by booleanPref("onboarded", defaultValue = false)
override var appOpenCount: Int
by intPref("appOpenCount", defaultValue = 0)
// nullable, null by default
override var username: String?
by stringPref("username")
}
: SimpleKrate(context), AppSetti
Krate*
myKrate.onboarded = true
myKrate.appOpenCount++
println(myKrate.username)
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class MyKrate @Inject constructor(context: Context)
// non-nullable, has default value
override var onboarded: Boolean
by booleanPref("onboarded", defaultValue = false)
override var appOpenCount: Int
by intPref("appOpenCount", defaultValue = 0)
// nullable, null by default
override var username: String?
by stringPref("username")
}
Krate*
myKrate.onboarded = true
myKrate.appOpenCount++
println(myKrate.username)
: SimpleKrate(context), AppSettings {
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References
• Krate
https://github.com/AutSoft/Krate
• Delightful Delegate Design
https://blog.autsoft.hu/delightful-delegate-design/
• Further reading
Maintaining Compatibility in Kotlin libraries
https://zsmb.co/maintaining-compatibility-in-kotlin-libraries/
Swift Pitch: Property Delegates
https://forums.swift.org/t/pitch-property-delegates/21895
DSL Design
https://zsmb.co/kotlin-dsl-design-with-village-dsl/
Tips for writing a library
https://www.kotlindevelopment.com/tips-for-writing-a-library-in-kotlin/
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Questions?
zsmb.co zsmb13
[email protected]
Photo by Agnieszka Kowalczyk on Unsplash