Building SDKs - The Kotlin Way

by Jossi Wolf
presented on August 30, 2019 @Kotlin/Everywhere Hamburg

Transcript

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5. Project Manager
   Developer
   Hey could you ship the
   new SDK version?
   

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6. Project Manager
   Developer
   Hey could you ship the
   new SDK version?
   S-s-sure…
   

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7. $ gradlew sdk:assembleRelease
   $ building…
   $ …
   $ # 10 hours later
   

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8. 3. Blah blah bla
   2. Bla blah bla
   1. Blah blah blah
   RELEASE
   NOTES
   

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9. 4. EXPERIMENTAL APIs.
   They are subject to
   change and not final!!!
   3. Blah blah bla
   2. Bla blah bla
   1. Blah blah blah
   RELEASE
   NOTES
   

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10. Project Manager
    Developer
    Cool, thanks
    Here’s the new
    Version!
    SDK
    

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11. 4. APIs have been removed.
    3. Blah blah bla
    2. Bla blah bla
    1. Blah blah blah
    RELEASE
    NOTES
    

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12. Project Manager
    Developer
    Cool, thanks
    Here’s the new
    Version!
    SDK
    

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13. Slack Message
    PROJECT MANAGER
    $CUSTOMER JUST CALLED THEY HAVE A BUILD
    ERROR WITH THE NEW SDK VERSION CAN YOU FIX
    THAT NOW PLS
    Friday, 9PM
    

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14. You: Have they read the release notes?
    PM: I’ll ask
    ...
    PM: No
    

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15. @Experimental
    @Deprecated
    

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16. @Target(ANNOTATION_CLASS)
    public annotation class Experimental(val level: Level =
    Level.ERROR) {
    public enum class Level {
    WARNING,
    ERROR,
    }
    }
    

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17. @Target(ANNOTATION_CLASS)
    public annotation class Experimental(val level: Level =
    Level.ERROR) {
    public enum class Level {
    WARNING,
    ERROR,
    }
    }
    

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18. @Target(ANNOTATION_CLASS)
    public annotation class Experimental(val level: Level =
    Level.ERROR) {
    public enum class Level {
    WARNING,
    ERROR,
    }
    }
    

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19. @Experimental
    annotation class ExperimentalCatPicturesAPI
    

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20. class CatPicturesAPI {
    /**
    * Experimental in case cats overtake the planet and
    * demand pets and treats in exchange for cat pictures
    */
    @ExperimentalCatPicturesAPI
    fun getCatPicture(): CatPicture = CatPicture()
    }
    

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21. fun doCatPictureAPIStuff() {
    val catPicturesAPI = CatPicturesAPI()
    catPicturesAPI.getCatPicture()
    } This API is experimental and its usage
    must be marked with @UseExperimental.
    

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22. @ExperimentalCatPicturesAPI
    fun doCatPictureAPIStuff() {
    val catPicturesAPI = CatPicturesAPI()
    catPicturesAPI.getCatPicture()
    }
    

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23. @UseExperimental(ExperimentalCatPicturesAPI::class)
    fun doCatPictureAPIStuff() {
    val catPicturesAPI = CatPicturesAPI()
    catPicturesAPI.getCatPicture()
    }
    

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24. Productive Developer
    

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25. Project Man
    Developer
    

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26. Project Manager
    Developer
    

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27. Project Manager
    Developer
    

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28. Project Manager
    Developer
    

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29. Project Manager
    Developer
    Hey could you ship the
    new SDK version?
    

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30. Project Manager
    Developer
    Hey could you ship the
    new SDK version?
    S-s-sure…
    

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31. 4. APIs have been
    deprecated.
    3. Blah blah bla
    2. Bla blah bla
    1. Blah blah blah
    RELEASE
    NOTES
    

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32. Project Manager
    Developer
    Cool, thanks
    Here’s the new
    Version!
    SDK
    Contains
    deprecated APIs
    

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33. Project Manager
    Cool, thanks
    SDK User
    Here’s the new
    Version!
    SDK
    Contains
    deprecated APIs
    

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34. BUILD ERROR
    SDK User
    SDK
    *updates SDK version*
    *runs Gradle build*
    

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35. /**
    * Marks the annotated declaration as deprecated.
    */ TYPEALIAS)
    annotation class Deprecated(
    val message: String,
    val replaceWith: ReplaceWith = ReplaceWith(""),
    val level: DeprecationLevel = DeprecationLevel.WARNING
    )
    

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36. @Deprecated(“This is a legacy API. Please use
    the new CatPicturesAPI instead.")
    class LegacyCatPictureAPI {
    fun getCatPicture(): CatPicture = CatPicture()
    }
    

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37. val api = LegacyCatPictureAPI()
    

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38. /**
    * Marks the annotated declaration as deprecated.
    */ TYPEALIAS)
    annotation class Deprecated(
    val message: String,
    val replaceWith: ReplaceWith = ReplaceWith(""),
    val level: DeprecationLevel = DeprecationLevel.WARNING
    )
    

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39. annotation class ReplaceWith(
    val expression: String,
    vararg val imports: String
    )
    

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40. @Deprecated(
    "This is a legacy API. Please use the new
    CatPicturesAPI instead.",
    ReplaceWith("CatPicturesAPI")
    )
    class LegacyCatPictureAPI {
    fun getCatPicture(): CatPicture = CatPicture()
    }
    

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41. @Deprecated(
    "This is a legacy API. Please use the new
    CatPicturesAPI instead.",
    ReplaceWith("CatPicturesAPI")
    )
    class LegacyCatPictureAPI {
    fun getCatPicture(): CatPicture = CatPicture()
    }
    

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42. val api = LegacyCatPictureAPI()
    Replace with ‘CatPicturesAPI’
    

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43. val api = LegacyCatPictureAPI()
    Replace with ‘CatPicturesAPI’
    Alt + Enter
    

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44. val api = CatPicturesAPI()
    ✔Occurrence Replaced!
    

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45. class Laboratory {
    fun getRandommChemical(): Chemical
    = randomExperiment + randomExperiment + explosive
    }
    

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46. class Laboratory {
    @Deprecated(
    "Typo in here. Please use getRandomChemical instead.",
    ReplaceWith("getRandomChemical")
    )
    fun getRandommChemical(): Chemical
    = randomExperiment + randomExperiment + explosive
    }
    

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47. class Laboratory {
    @Deprecated(
    "Typo in here. Please use getRandomChemical instead.",
    ReplaceWith("getRandomChemical")
    )
    fun getRandommChemical(): Chemical
    = randomExperiment + randomExperiment + explosive
    fun getRandomChemical(): Chemical
    = randomExperiment + randomExperiment + explosive
    }
    

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48. class Laboratory {
    @Deprecated(
    "Typo in here. Please use getRandomChemical instead.",
    ReplaceWith("getRandomChemical")
    )
    fun getRandommChemical(): Chemical
    = getRandomChemical()
    fun getRandomChemical(): Chemical
    = randomExperiment + randomExperiment + explosive
    }
    

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49. class CatPicturesAPI {
    /**
    * Experimental in case cats overtake the planet and
    * demand pets and treats in exchange for cat pictures
    */
    @ExperimentalCatPicturesAPI
    fun getCatPicture(): CatPicture = CatPicture()
    }
    

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50. class CatPictureAPI {
    /**
    * Experimental in case cats overtake the planet and
    * demand pets and treats in exchange for cat pictures
    */
    @ExperimentalCatPicturesAPI
    fun getCatPicture(): CatPicture = CatPicture()
    }
    

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51. @Deprecated(
    message = "CatPicturesAPI has been renamed
    to CatPictureAPI“,
    replaceWith = ReplaceWith("CatPictureAPI")
    )
    typealias CatPicturesAPI = CatPictureAPI
    

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53. SDK
    

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54. interface SDKCapabilities {
    ...
    }
    class ArtboardSDK: SDKCapabilities {
    //It'll become super bloated
    }
    

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55. interface CanvasCapabilities
    interface SDKCapabilities: CanvasCapabilities
    class ArtboardSDK: SDKCapabilities {
    val canvasManager = CanvasManager()
    override fun draw() = canvasManager.draw()
    }
    

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56. interface CanvasCapabilities
    interface SDKCapabilities: CanvasCapabilities
    class ArtboardSDK: SDKCapabilities {
    val canvasManager = CanvasManager()
    override fun draw() = canvasManager.draw()
    }
    

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57. interface CanvasCapabilities
    interface SDKCapabilities: CanvasCapabilities
    class ArtboardSDK: SDKCapabilities {
    val canvasManager = CanvasManager()
    override fun draw() = canvasManager.draw()
    }
    

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58. interface CanvasCapabilities
    interface SDKCapabilities: CanvasCapabilities
    class CanvasManager: CanvasCapabilities
    class ArtboardSDK:
    SDKCapabilities,
    CanvasCapabilities by CanvasManager()
    

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59. interface CanvasCapabilities
    interface SDKCapabilities: CanvasCapabilities
    class CanvasManager: CanvasCapabilities
    class ArtboardSDK:
    SDKCapabilities,
    CanvasCapabilities by CanvasManager()
    

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