KMP4FREE in 2023 @ Droidcon NYC 2022

Video: https://www.droidcon.com/2022/09/29/kmp4free-in-2023/

At Droidcon SF 2022, I first publicly announced the KMP4FREE Gradle Plugin and how it can be used to seamlessly toggle between the Kotlin JVM and Kotlin Multiplatform Plugins with a single line change. In this talk I'll show you what this will look like over the next year, and more real world examples of how this Gradle Plugin can be used. KMP4FREE can help you can start making your Kotlin code Multiplatform Compatible, today!

Transcript

1. Sam Edwards - @HandstandSam
   Kotlin & Android GDE @ Dropbox
   KMP4FREE
   in 2023
   Droidcon NYC 2022
   

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2. Sam Edwards - @HandstandSam
   Kotlin & Android GDE @ Dropbox
   Multiplaformization
   in 2023
   Droidcon NYC 2022
   

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3. https://twitter.com/relizarov/status/1564288780261068802
   KMP4FREE is a Tool to help with Multiplatformization
   

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4. K 4FREE
   MP
   

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5. Primary Goals of KMP4FREE
   • No Risk, Single Line Change to Enable Multiplatform
   
   • Support JVM & Multiplatform Con
   fi
   g
   
   • Allow Experimentation and Possible Migration to Multiplatform
   

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6. KMP4FREE Work?
   How Does
   

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7. JVM Project Structure
   plugins {
   kotlin("jvm")
   }
   dependencies {
   implementation(libs.kotlin.stdlib)
   implementation(project(":samples:jvm_kmp4free"))
   testImplementation(libs.kotlin.test.common)
   testImplementation(libs.truth)
   }
   

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8. JVM Project Structure
   plugins {
   id("com.handstandsam.kmp4free")
   }
   dependencies {
   implementation(libs.kotlin.stdlib)
   implementation(project(":samples:jvm_kmp4free"))
   testImplementation(libs.kotlin.test.common)
   testImplementation(libs.truth)
   }
   

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9. Enable/Disable with Property
   # gradle.properties
   kmp4free=true
   or
   ./gradlew … -Pkmp4free=true
   

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10. JVM Project Structure
    

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11. JVM Project Structure
    

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12. JVM Project Structure
    kmp4free=false
    

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13. JVM Project Structure
    kmp4free=true
    kmp4free=false
    

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14. JVM Project Structure
    kmp4free=true
    kmp4free=false
    

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15. JVM Project Structure
    kmp4free=true
    kmp4free=false
    

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16. Source Set and Con
    fi
    guration Mapping
    How?
    

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17. kmp4free=true
    • SourceSet Mapping
    • src/main ➡ src/commonMain
    
    • src/test ➡ src/jvmTest
    
    • Con
    fi
    guration Mapping
    • implementation ➡ commonMainImplementation
    
    • testImplementation ➡ jvmTestImplementation
    
    • Task Aliasing
    • :module:test ➡ :module:jvmTest
    

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18. kmp4free=false
    • SourceSet Mapping
    • src/commonMain ➡ src/main
    
    • src/jvmMain ➡ src/main
    
    • src/commonTest ➡ src/test
    
    • src/jvmTest ➡ src/test
    
    • Con
    fi
    guration Mapping
    • commonMainImplementation ➡ implementation
    
    • commonTestImplementation ➡ testImplementation
    
    • jvmTestImplementation ➡ testImplementation
    

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19. K 4FREE
    MP
    Demo
    

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20. Enable and Disable Multiplatform Targets?
    Can’t You Just
    

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21. Compiling Multiplatform Can Be Slow
    https://medium.com/yazio-engineering/speeding-up-kotlin-multiplatform-61ebf8dae560
    grade.properties
    

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22. Multiplatform Doesn’t Support Con
    fi
    guration Caching (Yet)
    https://youtrack.jetbrains.com/issue/KT-49933/Support-Gradle-Con
    fi
    guration-caching-with-HMPP
    

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23. Multiplatform Plugin Adds Overhead
    7 Tasks 14 Tasks
    

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24. Doesn’t Quite Work in Android Studio
    https://issuetracker.google.com/issues/229628556
    

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25. KMP4FREE?
    Should I Use
    

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26. but NOT Inde
    fi
    nitely
    It Depends
    

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27. to Multiplatform
    Finding Your Path
    

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28. Paths to Multiplatformization
    New Code
    

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29. Paths to Multiplatformization
    commonMain
    New Code
    

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30. Paths to Multiplatformization
    commonMain
    Existing Code
    New Code
    

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31. Paths to Multiplatformization
    Existing Code
    commonMain
    New Code
    KMP4FREE?
    

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32. Paths to Multiplatformization
    Existing Code
    commonMain
    KMP4FREE?
    

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33. Shapes The Future
    Every Decision
    

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34. Has Consequences
    Every Decision
    

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35. On Kotlin
    Going All In
    

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36. On Compose
    Going All In
    

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37. On Multiplatform
    Going All In
    

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38. Mitigation
    Risk
    

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39. From The Past
    Learn
    

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40. 🤔
    https://dropbox.tech/mobile/the-not-so-hidden-cost-of-sharing-code-between-ios-and-android
    

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41. “By writing code in a non-standard fashion, we
    took on overhead that we would have not had
    to worry about had we stayed with the widely
    used platform defaults. This overhead ended
    up being more expensive than just writing the
    code twice.”
    

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42. The Overhead of:
    1. Custom frameworks and libraries
    2. Custom development environment
    3. Addressing di
    ff
    erences between the platforms
    4. Training, hiring, and retaining developers
    

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43. Write Kotlin Multiplatform Code?
    When Will Your Team
    

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44. with KMP4FREE
    Starting Now
    

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45. Ship Kotlin Multiplatform Code on iOS?
    When Will Your Team
    

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46. Maybe Never?
    ¯\_(ツ)_/¯
    

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47. For Kotlin Multiplatform
    Plant a Seed 🌱
    

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48. …And It Might Grow 🌲
    

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49. Plant a Seed 🌱
    • Same Kotlin Code
    
    • Di
    ff
    erent Gradle plugin
    
    • Forces modularity
    
    • Makes developers more likely to try coding in the other platform
    

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50. Identifying
    Target Projects
    

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51. Plugins
    Kotlin + Gradle
    

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52. Gradle Plugin Migration
    kotlin(“android”)
    

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53. Gradle Plugin Migration
    kotlin(“android”)
    kotlin(“jvm”)
    

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54. Gradle Plugin Migration
    kotlin(“android”)
    kotlin(“jvm”)
    kotlin(“multiplatform”)
    

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55. Android Library Kotlin JVM
    Step 1
    ➡
    

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56. dependency-analysis-android-gradle-plugin
    github.com/autonomousapps/dependency-analysis-android-gradle-plugin
    

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57. dependency-analysis-android-gradle-plugin
    1. Gathers Module Data
    2. Runs Decisioning Logic
    3. Shares Actionable Advice
    

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58. data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    Android Library ➡ JVM Module Advice
    

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59. data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    Android Library ➡ JVM Module Advice
    

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60. data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    Android Library ➡ JVM Module Advice
    

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61. data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    Android Library ➡ JVM Module Advice
    

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62. data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    Android Library ➡ JVM Module Advice
    

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63. data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    Android Library ➡ JVM Module Advice
    

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64. @TypeLabel("android_score")
    @JsonClass(generateAdapter = false)
    data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    @delegate:Transient
    private val score: Float by unsafeLazy {
    var count = 0f
    if (hasAndroidAssets) count += 2
    if (hasAndroidRes) count += 2
    if (usesAndroidClasses) count += 2
    if (hasBuildConfig) count += 0.5f
    if (hasAndroidDependencies) count += 0.5f
    count
    }
    Android Library ➡ JVM Module Advice
    

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65. @TypeLabel("android_score")
    @JsonClass(generateAdapter = false)
    data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    @delegate:Transient
    private val score: Float by unsafeLazy {
    var count = 0f
    if (hasAndroidAssets) count += 2
    if (hasAndroidRes) count += 2
    if (usesAndroidClasses) count += 2
    if (hasBuildConfig) count += 0.5f
    if (hasAndroidDependencies) count += 0.5f
    count
    }
    Android Library ➡ JVM Module Advice
    

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66. /** True if this project uses no Android facilities at all. */
    fun shouldBeJvm(): Boolean = score == 0f
    Android Library ➡ JVM Module Advice
    @TypeLabel("android_score")
    @JsonClass(generateAdapter = false)
    data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    @delegate:Transient
    private val score: Float by unsafeLazy {
    var count = 0f
    if (hasAndroidAssets) count += 2
    if (hasAndroidRes) count += 2
    if (usesAndroidClasses) count += 2
    if (hasBuildConfig) count += 0.5f
    if (hasAndroidDependencies) count += 0.5f
    count
    }
    

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67. /** True if this project uses no Android facilities at all. */
    fun shouldBeJvm(): Boolean = score == 0f
    /** True if this project only uses some limited number of Android facilities. */
    fun couldBeJvm(): Boolean = score < THRESHOLD
    Android Library ➡ JVM Module Advice
    @TypeLabel("android_score")
    @JsonClass(generateAdapter = false)
    data class AndroidScore(
    val hasAndroidAssets: Boolean,
    val hasAndroidRes: Boolean,
    val usesAndroidClasses: Boolean,
    val hasBuildConfig: Boolean,
    val hasAndroidDependencies: Boolean,
    ) : ModuleAdvice() {
    @delegate:Transient
    private val score: Float by unsafeLazy {
    var count = 0f
    if (hasAndroidAssets) count += 2
    if (hasAndroidRes) count += 2
    if (usesAndroidClasses) count += 2
    if (hasBuildConfig) count += 0.5f
    if (hasAndroidDependencies) count += 0.5f
    count
    }
    

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68. Module Advice from ./gradlew buildHealth
    Advice for :samples:android_lib
    
    
    Module structure advice
    
    
    This project uses limited Android features and could be a JVM project.
    
    
    * Includes BuildConfig.
    
    
    

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69. Refactoring is Rarely Trivial
    

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70. Extract Android Specific Code
    • Android Classes
    • BuildCon
    fi
    g
    • Assets
    • Strings
    • Activities
    • Layouts
    • Drawables
    

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71. Kotlin JVM Kotlin Multiplatform
    Step 2
    ➡
    

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72. KMP-Readiness
    github.com/handstandsam/kmp-readiness
    

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73. KMP-Readiness Decisioning
    1. Multiplatform Plugin Already Enabled?
    2. Only Kotlin Code?
    3. References to java.util, etc?
    4. Multiplatform Compatible Dependencies?
    

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74. Multiplatform Compatible
    Dependencies?
    

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78. 9 Days Later …
    

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80. Maven Search
    https://search.maven.org/search?q=ktor-client
    

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81. Maven Search JSON API
    https://search.maven.org/solrsearch/select?q=g%3Aorg.jetbrains.kotlinx+AND+a%3Akotlinx-datetime+AND+v%3A0.3.2+AND+p%3Ajar+AND+l%3Akotlin-tooling-metadata&rows=1&wt=json
    {
    "response": {
    "numFound": 1,
    "start": 0,
    "docs": [
    {
    "id": "org.jetbrains.kotlinx:kotlinx-datetime:0.3.2",
    "g": "org.jetbrains.kotlinx",
    "a": "kotlinx-datetime",
    "v": "0.3.2",
    "p": "jar",
    "timestamp": 1641926665000,
    "ec": [
    "-javadoc.jar",
    "-sources.jar",
    ".jar",
    "-all.jar",
    "-kotlin-tooling-metadata.json",
    ".module",
    ".pom"
    ],
    "tags": [
    "kotlin",
    "library",
    "datetime"
    ]
    }
    ]
    }
    }
    https://search.maven.org/search?q=g:org.jetbrains.kotlinx%20AND%20a:kotlinx-datetime%20AND%20v:0.3.2%20AND%20p:jar%20AND%20l:kotlin-tooling-metadata
    

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82. Maven Search JSON API
    https://search.maven.org/solrsearch/select?q=g%3Aorg.jetbrains.kotlinx+AND+a%3Akotlinx-datetime+AND+v%3A0.3.2+AND+p%3Ajar+AND+l%3Akotlin-tooling-metadata&rows=1&wt=json
    "-kotlin-tooling-metadata.json"
    

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83. kotlin-metadata-tooling.json
    

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84. {
    "schemaVersion": "1.0.0",
    "buildSystem": "Gradle",
    "buildSystemVersion": "7.5.1",
    "buildPlugin": "org.jetbrains.kotlin.gradle.plugin.KotlinMultiplatformPluginWrapper",
    "buildPluginVersion": "1.6.21",
    "projectSettings": {
    "isHmppEnabled": true,
    "isCompatibilityMetadataVariantEnabled": true
    },
    "projectTargets": [
    {
    "target": "org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget",
    "platformType": "jvm",
    "extras": {
    "jvm": {
    "jvmTarget": "1.8",
    "withJavaEnabled": false
    }
    }
    },
    {
    "target": "org.jetbrains.kotlin.gradle.plugin.mpp.KotlinMetadataTarget",
    "platformType": "common"
    }
    ]
    }
    kotlin-tooling-metadata.json
    https://repo1.maven.org/maven2/io/ktor/ktor-client/2.1.0/ktor-client-2.1.0-kotlin-tooling-metadata.json
    

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85. "platformType": "common"
    kotlin-tooling-metadata.json
    https://repo1.maven.org/maven2/io/ktor/ktor-client/2.1.0/ktor-client-2.1.0-kotlin-tooling-metadata.json
    

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86. See Created kotlin-tooling-metadata.json for the Kotlin Team
    

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87. February 2nd, 2021 - Kotlin Lang Slack
    

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88. kdoctor
    https://github.com/Kotlin/kdoctor
    

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89. KMP-readiness
    github.com/handstandsam/kmp-readiness
    Demo
    

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90. …
    

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91. Kotlin Multiplatform
    Multiplatformization Success!
    

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92. What’s the Cost?
    

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93. Upfront Investment, Low Risk, …
    

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94. Run Anywhere*
    Write Once
    * Yes, but…
    

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95. Coming Soon!
    Kotlin Multiplatform Beta
    

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96. Minimize Risk during Multiplatformization
    We Can
    

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97. Test and Experiment ♻
    • Create a multiplatform iOS and Desktop app that exercises it
    
    • Create Shadow Jobs to Build Multiplatform to ensure compatibility
    

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98. 2023 is the Year of
    Multiplatformization
    

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99. Is a helpful tool on your path to Multiplaformization in 2023
    KMP4FREE
    

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100. Is a helpful tool on your path to Multiplaformization in 2023
     KMP-Readiness
     

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101. With Multiplatform in Mind
     Write Code
     

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102. Thank You
     

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