Mixing
How to define custom JS objects in ScalaJS
The phaser game library has an API where you pass a custom object when starting a game scene (docs). This data object can be any javascript object at all and can be retrieved from within the scene from the scene's settings. My question is how do I define this object in the phaser facades in a generic way and define a strongly typed version in my own code?
So far I have just referenced the object as a js.Object in the phaser APIs and cast it to my own type when the scene is created:
@js.native
trait ScenePlugin extends js.Object {
def start(key: SceneKey, data: js.UndefOr[js.Object] = js.undefined): ScenePlugin
}
@js.annotation.ScalaJSDefined
class LevelConfig(
val key: LevelKey,
val loadingImage: Option[AssetKey] = None) extends js.Object
@ScalaJSDefined
class LoadScene extends Scene {
private val loader = new SceneLoader(scene = this)
private var levelConfig: LevelConfig = _
override def preload(): Unit = {
levelConfig = sys.settings.data.asInstanceOf[LevelConfig]
}
...
}
This works but I'm not happy with it because I have to cast the data object. Any errors with the actual object that gets passed to the ScenePlugin.start() will cause errors during runtime and I may as well have just used vanilla JS. Also, my LevelConfig cannot be a case class as I get the compile error Classes and objects extending js.Any may not have a case modifier which I don't fully understand.
Has anyone dealt with this situation before and what did you do to get around it? I'm guessing the issue stems from the library which is being used so perhaps I need to create some kind of wrapper around Phaser's Scene class to deal with this? I'm quite new to ScalaJS and am looking to improve my understanding so any explanations with solutions would be much appreciated (and upvoted). Thanks very much!
phaser-framework scala.js
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
add a comment |
The phaser game library has an API where you pass a custom object when starting a game scene (docs). This data object can be any javascript object at all and can be retrieved from within the scene from the scene's settings. My question is how do I define this object in the phaser facades in a generic way and define a strongly typed version in my own code?
So far I have just referenced the object as a js.Object in the phaser APIs and cast it to my own type when the scene is created:
@js.native
trait ScenePlugin extends js.Object {
def start(key: SceneKey, data: js.UndefOr[js.Object] = js.undefined): ScenePlugin
}
@js.annotation.ScalaJSDefined
class LevelConfig(
val key: LevelKey,
val loadingImage: Option[AssetKey] = None) extends js.Object
@ScalaJSDefined
class LoadScene extends Scene {
private val loader = new SceneLoader(scene = this)
private var levelConfig: LevelConfig = _
override def preload(): Unit = {
levelConfig = sys.settings.data.asInstanceOf[LevelConfig]
}
...
}
This works but I'm not happy with it because I have to cast the data object. Any errors with the actual object that gets passed to the ScenePlugin.start() will cause errors during runtime and I may as well have just used vanilla JS. Also, my LevelConfig cannot be a case class as I get the compile error Classes and objects extending js.Any may not have a case modifier which I don't fully understand.
Has anyone dealt with this situation before and what did you do to get around it? I'm guessing the issue stems from the library which is being used so perhaps I need to create some kind of wrapper around Phaser's Scene class to deal with this? I'm quite new to ScalaJS and am looking to improve my understanding so any explanations with solutions would be much appreciated (and upvoted). Thanks very much!
phaser-framework scala.js
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
Question: do you want to define the facade in the completely-generic way? If the facade is highly-general (allowing varied types), then your strongly-typed code isn't going to have much choice but to cast. But keep in mind that your facade can be stricter than the underlying JS library, provided that it sufficiently describes all the data you will be passing back and forth.
– Justin du Coeur
Jan 2 at 23:42
I don't really care about what type the facade has as long as it's not hard-coded to a specific object. Each game will have have multiple scene objects which may have different data objects passed to them.
– William Carter
Jan 3 at 18:43
1
In which case, the cast may be a necessary evil. This isn't actually unusual -- Scala.js is the exception to the usual rule that you should always avoidasInstanceOf. When you are at the border between strongly-typed Scala and weakly-typed JavaScript, it's often necessary. I usually wrap the casts in API code, and then call those APIs from my application code.
– Justin du Coeur
Jan 3 at 23:05
add a comment |
The phaser game library has an API where you pass a custom object when starting a game scene (docs). This data object can be any javascript object at all and can be retrieved from within the scene from the scene's settings. My question is how do I define this object in the phaser facades in a generic way and define a strongly typed version in my own code?
So far I have just referenced the object as a js.Object in the phaser APIs and cast it to my own type when the scene is created:
@js.native
trait ScenePlugin extends js.Object {
def start(key: SceneKey, data: js.UndefOr[js.Object] = js.undefined): ScenePlugin
}
@js.annotation.ScalaJSDefined
class LevelConfig(
val key: LevelKey,
val loadingImage: Option[AssetKey] = None) extends js.Object
@ScalaJSDefined
class LoadScene extends Scene {
private val loader = new SceneLoader(scene = this)
private var levelConfig: LevelConfig = _
override def preload(): Unit = {
levelConfig = sys.settings.data.asInstanceOf[LevelConfig]
}
...
}
This works but I'm not happy with it because I have to cast the data object. Any errors with the actual object that gets passed to the ScenePlugin.start() will cause errors during runtime and I may as well have just used vanilla JS. Also, my LevelConfig cannot be a case class as I get the compile error Classes and objects extending js.Any may not have a case modifier which I don't fully understand.
Has anyone dealt with this situation before and what did you do to get around it? I'm guessing the issue stems from the library which is being used so perhaps I need to create some kind of wrapper around Phaser's Scene class to deal with this? I'm quite new to ScalaJS and am looking to improve my understanding so any explanations with solutions would be much appreciated (and upvoted). Thanks very much!
phaser-framework scala.js
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
The phaser game library has an API where you pass a custom object when starting a game scene (docs). This data object can be any javascript object at all and can be retrieved from within the scene from the scene's settings. My question is how do I define this object in the phaser facades in a generic way and define a strongly typed version in my own code?
So far I have just referenced the object as a js.Object in the phaser APIs and cast it to my own type when the scene is created:
@js.native
trait ScenePlugin extends js.Object {
def start(key: SceneKey, data: js.UndefOr[js.Object] = js.undefined): ScenePlugin
}
@js.annotation.ScalaJSDefined
class LevelConfig(
val key: LevelKey,
val loadingImage: Option[AssetKey] = None) extends js.Object
@ScalaJSDefined
class LoadScene extends Scene {
private val loader = new SceneLoader(scene = this)
private var levelConfig: LevelConfig = _
override def preload(): Unit = {
levelConfig = sys.settings.data.asInstanceOf[LevelConfig]
}
...
}
This works but I'm not happy with it because I have to cast the data object. Any errors with the actual object that gets passed to the ScenePlugin.start() will cause errors during runtime and I may as well have just used vanilla JS. Also, my LevelConfig cannot be a case class as I get the compile error Classes and objects extending js.Any may not have a case modifier which I don't fully understand.
Has anyone dealt with this situation before and what did you do to get around it? I'm guessing the issue stems from the library which is being used so perhaps I need to create some kind of wrapper around Phaser's Scene class to deal with this? I'm quite new to ScalaJS and am looking to improve my understanding so any explanations with solutions would be much appreciated (and upvoted). Thanks very much!
phaser-framework scala.js
phaser-framework scala.js
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
asked Jan 2 at 23:23
William CarterWilliam Carter
765819
765819
Question: do you want to define the facade in the completely-generic way? If the facade is highly-general (allowing varied types), then your strongly-typed code isn't going to have much choice but to cast. But keep in mind that your facade can be stricter than the underlying JS library, provided that it sufficiently describes all the data you will be passing back and forth.
– Justin du Coeur
Jan 2 at 23:42
I don't really care about what type the facade has as long as it's not hard-coded to a specific object. Each game will have have multiple scene objects which may have different data objects passed to them.
– William Carter
Jan 3 at 18:43
1
In which case, the cast may be a necessary evil. This isn't actually unusual -- Scala.js is the exception to the usual rule that you should always avoidasInstanceOf. When you are at the border between strongly-typed Scala and weakly-typed JavaScript, it's often necessary. I usually wrap the casts in API code, and then call those APIs from my application code.
– Justin du Coeur
Jan 3 at 23:05
add a comment |
Question: do you want to define the facade in the completely-generic way? If the facade is highly-general (allowing varied types), then your strongly-typed code isn't going to have much choice but to cast. But keep in mind that your facade can be stricter than the underlying JS library, provided that it sufficiently describes all the data you will be passing back and forth.
– Justin du Coeur
Jan 2 at 23:42
I don't really care about what type the facade has as long as it's not hard-coded to a specific object. Each game will have have multiple scene objects which may have different data objects passed to them.
– William Carter
Jan 3 at 18:43
1
In which case, the cast may be a necessary evil. This isn't actually unusual -- Scala.js is the exception to the usual rule that you should always avoidasInstanceOf. When you are at the border between strongly-typed Scala and weakly-typed JavaScript, it's often necessary. I usually wrap the casts in API code, and then call those APIs from my application code.
– Justin du Coeur
Jan 3 at 23:05
Question: do you want to define the facade in the completely-generic way? If the facade is highly-general (allowing varied types), then your strongly-typed code isn't going to have much choice but to cast. But keep in mind that your facade can be stricter than the underlying JS library, provided that it sufficiently describes all the data you will be passing back and forth.
– Justin du Coeur
Jan 2 at 23:42
Question: do you want to define the facade in the completely-generic way? If the facade is highly-general (allowing varied types), then your strongly-typed code isn't going to have much choice but to cast. But keep in mind that your facade can be stricter than the underlying JS library, provided that it sufficiently describes all the data you will be passing back and forth.
– Justin du Coeur
Jan 2 at 23:42
I don't really care about what type the facade has as long as it's not hard-coded to a specific object. Each game will have have multiple scene objects which may have different data objects passed to them.
– William Carter
Jan 3 at 18:43
I don't really care about what type the facade has as long as it's not hard-coded to a specific object. Each game will have have multiple scene objects which may have different data objects passed to them.
– William Carter
Jan 3 at 18:43
1
1
In which case, the cast may be a necessary evil. This isn't actually unusual -- Scala.js is the exception to the usual rule that you should always avoid
asInstanceOf. When you are at the border between strongly-typed Scala and weakly-typed JavaScript, it's often necessary. I usually wrap the casts in API code, and then call those APIs from my application code.– Justin du Coeur
Jan 3 at 23:05
In which case, the cast may be a necessary evil. This isn't actually unusual -- Scala.js is the exception to the usual rule that you should always avoid
asInstanceOf. When you are at the border between strongly-typed Scala and weakly-typed JavaScript, it's often necessary. I usually wrap the casts in API code, and then call those APIs from my application code.– Justin du Coeur
Jan 3 at 23:05
add a comment |
1 Answer
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I followed Justin du Coeur's comment suggestion of modifying the Phaser facade's. I defined a non-native trait for a SceneData object and updated the native Scene facade to have two types which subclasses of Scene must override. Phaser scenes are abstract and intended to be overridden so I think this works well:
class Scene(config: SceneConfig) extends js.Object {
type Key <: SceneKey
type Data <: SceneData
def scene: ScenePlugin = js.native
def data: Data = js.native
def preload(): Unit = js.native
def create(): Unit = js.native
def update(time: Double, delta: Double): Unit = js.native
}
object Scene {
trait SceneKey { def value: String }
implicit def keyAsString(id: SceneKey): String = id.value
trait SceneData extends js.Object
}
@js.native
trait ScenePlugin extends js.Object {
def start[S <: Scene](id: String, data: js.UndefOr[S#Data] = js.undefined): ScenePlugin = js.native
}
And here's a simplified example of a scene in my game:
class LoadScene extends Scene(LoadScene.Config) {
override type Key = LoadId.type
override type Data = GameAssets
override def preload(): Unit = {
createLoadBar()
loadAssets(data)
}
private def createLoadBar(): Unit = { ... }
private def loadAssets(config: GameAssets): Unit = { ... }
override def create(): Unit = {
scene.start[GameScene](GameId)
}
}
object LoadScene {
case object LoadId extends SceneKey { val value = "loading" }
val Config: SceneConfig = ...
}
I quite like this because it's now impossible to start a scene with another scene's config type.
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
add a comment |
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I followed Justin du Coeur's comment suggestion of modifying the Phaser facade's. I defined a non-native trait for a SceneData object and updated the native Scene facade to have two types which subclasses of Scene must override. Phaser scenes are abstract and intended to be overridden so I think this works well:
class Scene(config: SceneConfig) extends js.Object {
type Key <: SceneKey
type Data <: SceneData
def scene: ScenePlugin = js.native
def data: Data = js.native
def preload(): Unit = js.native
def create(): Unit = js.native
def update(time: Double, delta: Double): Unit = js.native
}
object Scene {
trait SceneKey { def value: String }
implicit def keyAsString(id: SceneKey): String = id.value
trait SceneData extends js.Object
}
@js.native
trait ScenePlugin extends js.Object {
def start[S <: Scene](id: String, data: js.UndefOr[S#Data] = js.undefined): ScenePlugin = js.native
}
And here's a simplified example of a scene in my game:
class LoadScene extends Scene(LoadScene.Config) {
override type Key = LoadId.type
override type Data = GameAssets
override def preload(): Unit = {
createLoadBar()
loadAssets(data)
}
private def createLoadBar(): Unit = { ... }
private def loadAssets(config: GameAssets): Unit = { ... }
override def create(): Unit = {
scene.start[GameScene](GameId)
}
}
object LoadScene {
case object LoadId extends SceneKey { val value = "loading" }
val Config: SceneConfig = ...
}
I quite like this because it's now impossible to start a scene with another scene's config type.
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
add a comment |
I followed Justin du Coeur's comment suggestion of modifying the Phaser facade's. I defined a non-native trait for a SceneData object and updated the native Scene facade to have two types which subclasses of Scene must override. Phaser scenes are abstract and intended to be overridden so I think this works well:
class Scene(config: SceneConfig) extends js.Object {
type Key <: SceneKey
type Data <: SceneData
def scene: ScenePlugin = js.native
def data: Data = js.native
def preload(): Unit = js.native
def create(): Unit = js.native
def update(time: Double, delta: Double): Unit = js.native
}
object Scene {
trait SceneKey { def value: String }
implicit def keyAsString(id: SceneKey): String = id.value
trait SceneData extends js.Object
}
@js.native
trait ScenePlugin extends js.Object {
def start[S <: Scene](id: String, data: js.UndefOr[S#Data] = js.undefined): ScenePlugin = js.native
}
And here's a simplified example of a scene in my game:
class LoadScene extends Scene(LoadScene.Config) {
override type Key = LoadId.type
override type Data = GameAssets
override def preload(): Unit = {
createLoadBar()
loadAssets(data)
}
private def createLoadBar(): Unit = { ... }
private def loadAssets(config: GameAssets): Unit = { ... }
override def create(): Unit = {
scene.start[GameScene](GameId)
}
}
object LoadScene {
case object LoadId extends SceneKey { val value = "loading" }
val Config: SceneConfig = ...
}
I quite like this because it's now impossible to start a scene with another scene's config type.
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
add a comment |
I followed Justin du Coeur's comment suggestion of modifying the Phaser facade's. I defined a non-native trait for a SceneData object and updated the native Scene facade to have two types which subclasses of Scene must override. Phaser scenes are abstract and intended to be overridden so I think this works well:
class Scene(config: SceneConfig) extends js.Object {
type Key <: SceneKey
type Data <: SceneData
def scene: ScenePlugin = js.native
def data: Data = js.native
def preload(): Unit = js.native
def create(): Unit = js.native
def update(time: Double, delta: Double): Unit = js.native
}
object Scene {
trait SceneKey { def value: String }
implicit def keyAsString(id: SceneKey): String = id.value
trait SceneData extends js.Object
}
@js.native
trait ScenePlugin extends js.Object {
def start[S <: Scene](id: String, data: js.UndefOr[S#Data] = js.undefined): ScenePlugin = js.native
}
And here's a simplified example of a scene in my game:
class LoadScene extends Scene(LoadScene.Config) {
override type Key = LoadId.type
override type Data = GameAssets
override def preload(): Unit = {
createLoadBar()
loadAssets(data)
}
private def createLoadBar(): Unit = { ... }
private def loadAssets(config: GameAssets): Unit = { ... }
override def create(): Unit = {
scene.start[GameScene](GameId)
}
}
object LoadScene {
case object LoadId extends SceneKey { val value = "loading" }
val Config: SceneConfig = ...
}
I quite like this because it's now impossible to start a scene with another scene's config type.
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
I followed Justin du Coeur's comment suggestion of modifying the Phaser facade's. I defined a non-native trait for a SceneData object and updated the native Scene facade to have two types which subclasses of Scene must override. Phaser scenes are abstract and intended to be overridden so I think this works well:
class Scene(config: SceneConfig) extends js.Object {
type Key <: SceneKey
type Data <: SceneData
def scene: ScenePlugin = js.native
def data: Data = js.native
def preload(): Unit = js.native
def create(): Unit = js.native
def update(time: Double, delta: Double): Unit = js.native
}
object Scene {
trait SceneKey { def value: String }
implicit def keyAsString(id: SceneKey): String = id.value
trait SceneData extends js.Object
}
@js.native
trait ScenePlugin extends js.Object {
def start[S <: Scene](id: String, data: js.UndefOr[S#Data] = js.undefined): ScenePlugin = js.native
}
And here's a simplified example of a scene in my game:
class LoadScene extends Scene(LoadScene.Config) {
override type Key = LoadId.type
override type Data = GameAssets
override def preload(): Unit = {
createLoadBar()
loadAssets(data)
}
private def createLoadBar(): Unit = { ... }
private def loadAssets(config: GameAssets): Unit = { ... }
override def create(): Unit = {
scene.start[GameScene](GameId)
}
}
object LoadScene {
case object LoadId extends SceneKey { val value = "loading" }
val Config: SceneConfig = ...
}
I quite like this because it's now impossible to start a scene with another scene's config type.
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
edited Jan 5 at 12:54
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
answered Jan 5 at 12:46
William CarterWilliam Carter
765819
765819
add a comment |
add a comment |
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Question: do you want to define the facade in the completely-generic way? If the facade is highly-general (allowing varied types), then your strongly-typed code isn't going to have much choice but to cast. But keep in mind that your facade can be stricter than the underlying JS library, provided that it sufficiently describes all the data you will be passing back and forth.
– Justin du Coeur
Jan 2 at 23:42
I don't really care about what type the facade has as long as it's not hard-coded to a specific object. Each game will have have multiple scene objects which may have different data objects passed to them.
– William Carter
Jan 3 at 18:43
1
In which case, the cast may be a necessary evil. This isn't actually unusual -- Scala.js is the exception to the usual rule that you should always avoid
asInstanceOf. When you are at the border between strongly-typed Scala and weakly-typed JavaScript, it's often necessary. I usually wrap the casts in API code, and then call those APIs from my application code.– Justin du Coeur
Jan 3 at 23:05