PixiJS (or rather, Resource Loader), returns a JS object shaped like this in the callback of the load function:
{
"resource-you-asked-for.png": {
url: "foo.png",
error: <optional error>,
data: <binary data>
},
"second-resource.png": { ... }
}
My question is...how do I model this in Kotlin.js? I can't just say this is a Map<String, LoaderResult> -- then Kotlin will try to use get (a mangled get actually) to index into it. And I can't subclass dynamic obviously.
Suggestions?
JavaScript object that acts like a Map can be used in Kotlin as external interface with extension get and set operator functions:
external interface ResourceDictionary
inline operator fun ResourceDictionary.get(name: String): LoaderResult? =
this.asDynamic()[name]
inline operator fun ResourceDictionary.set(name: String, result: LoaderResult?) {
this.asDynamic()[name] = result
}
JavaScript object that acts like a class be used in Kotlin as external class
external open class LoaderResult {
var url: String
var data: ByteArray
var error: Error?
}
You can also convert TypeScript definitions using ts2kt tool:
$ npm install -g ts2kt
Find index.d.ts file for PixiJS
$ ts2kt index.d.ts
Then you'll be able to find external interface ResourceDictionary and external open class Resource in pixi.PIXI.loaders.kt:
Related
I have Kotlin some code that works as a class but when I try and run it as a Kotlin script I am getting " error: 'getNameAndVersion' is a member and an extension at the same time. References to such elements are not allowed"
enum class Env { Test, Sit }
data class ImageVersions(val apiName: String, val versions: Map<Env, String?>)
fun String.getNameAndVersion() = substringBefore(':') to substringAfter(':')
val testList = listOf("api-car-v1:0.0.118", "api-dog-v1:0.0.11", "api-plane-v1:0.0.36")
val sitList = listOf("api-car-v1:0.0.119", "api-plane-v1:0.0.37", "api-dog-v1:0.0.12")
getVersions(
mapOf(
Env.Test to testList,
Env.Sit to sitList
)
).forEach(::println)
fun getVersions(envMap: Map<Env, List<String>>): List<ImageVersions> {
val envApiNameMap = envMap.mapValues { it.value.associate(String::getNameAndVersion) }
val allApiNames = envApiNameMap.flatMap { it.value.keys }.distinct()
return allApiNames.map { apiName ->
ImageVersions(apiName, envApiNameMap.mapValues { it.value[apiName] })
}
}
I don't think I'm doing anything wrong with the way I'm using the method reference but according to my compiler I'm wrong. Appreciate some help with this. thanks
kotlinc -script .\myscript.kts
error: 'getNameAndVersion' is a member and an extension at the same time. References to such elements are not allowed
I don't have any experience with scripts but this error occurs when you try to reference a function inside a class that is also an extension function. (Here it is pointing to String::getNameAndVersion). Maybe when you run a script, the entire code is wrapped inside a class and then executed.
To fix this you can do one of the following:
Convert the function to a normal function which accepts a String parameter.
fun getNameAndVersion(s: String) = s.substringBefore(':') to s.substringAfter(':')
And replace String::getNameAndVersion with just ::getNameAndVersion in associate function
Other option is to directly call the function in the associate's lambda instead of passing a reference of this function.
.associate { it.getNameAndVersion() }
i am getting error - This class does not have constructor at object : TypeToken<List<Todo>>() + object is not abstract and does not implement object member
data class Todo(
val identifier: Long ,
val name: String ,
val description: String
)
class DefaultData {
private lateinit var myService: MyService
#PostConstruct
fun initializeDefault() {
val fileContent = this::class.java.classLoader.getResource("example.json").readText()
val todos: List<Todo> = Gson().fromJson(fileContent, object : TypeToken<List<Todo>>() {}.type)
myService.createTodoFromJsontodos
}
}
how can I fix this?
Objective is : To be able to create an endpoint that can get data from json file via service
Is there is a full fledged example
Also how to create interfaces in Ktor? As I want to use Dependency Inversion to enable retrieving data from different sources
Kotlin has built-in util similar to TypeToken, so I suggest using it instead:
Gson().fromJson(fileContent, typeOf<List<Todo>>().javaType)
You will need to add a dependency to kotlin-reflect. typeOf() function is marked as experimental, but I use it for some time already and never had any problems with it.
Also, you said in your comment that this is a starter project. If you don't have any existing code already then I suggest to use kotlinx-serialization instead of Gson. It is a de facto standard in Kotlin.
You can easily take advantage of kotlinx-serialization.
Steps:
Add the kotlin serialization plugin in your build.gradle file
kotlin("plugin.serialization") version "1.5.20"
plugins {
application
java
id("org.jetbrains.kotlin.jvm") version "1.5.21"
kotlin("plugin.serialization") version "1.5.20"
}
Add the dependecy for serialization library
dependencies {
...
implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.2.2")
}
Decode your json string to corresponding object using Json decode method
val JSON = Json {isLenient = true}
val mytodos = JSON.decodeFromString(message) as List<Todo>
Currently, I'm creating a function, which is available for the dependencies block in Groovy with:
project.dependencies.ext.foo = { String value ->
project.files(extension.getFooDependency(project).jarFiles).asFileTree
}
Thanks to that, I'm able to do:
afterEvaluate {
dependencies {
compileOnly foo('junit')
}
}
I'm converting the Groovy code to Kotlin, and I'm wondering how to rewrite this foo extension.
I've ended up with:
project.dependencies.extensions.extraProperties.set("foo", Action { value: String ->
project.files(extension.getIdeaDependency(project).jarFiles).asFileTree
})
After calling foo('junit'), I get the following exception:
> Could not find method foo() for arguments [junit] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.
I do not think that would work the same way in Kotlin DSL. Instead, you may declare a Kotlin extension function somewhere in the project. Then calling it would include all necessary receivers to you.
For multiple projects, I would recommend using a buildSrc project. Declarations there are visible to all project files below.
Speaking about Groovy and Kotlin support, I would do something like that:
private fun getFooImpl(scope: getFooImpl, name: String) { /*here is the implementation */ }
fun DependencyHandlerScope.getFoo(name:String) = getFooImpl(this, name)
//in Groovy
project.dependencies.extensions.extraProperties.set("foo", {getFooImpl(..)})
The same code could fit into a plugin as well. A more generic way could be to register a custom DLS extension, so to allow a custom block-like thisIsMyPlugin { .. } in the Gradle DSL and define all necessary helper functions in the extension class. Here the downside is in forcing users to wrap their code into the thisIsMyPlugin block.
my question is about creating javascript structure within KotlinJS and use them calling external modules.
Let's say we have the following js code and we want to translate it into KotlinJS.
const config = {
defs : "something",
resolvers : {
Query: {
books: () => []
}}
};
myFunction(config) // This can be any kind of external js function that accepts the above structure
How do we represent that config structure above using Kotlin JS? Is there an easy way to handle structures/json Kotlin side? Can we declare in some way that structure as dynamic?
Using Kotlin objects doesn't help.
As of now you gotta introduce interface and it's implementation, so it would be something like this:
external interface ConfigInterface {
var defs: String,
var resolvers: QueryHolder
}
external interface QueryHolder {
var Query: BookProcessor
}
external interface BookProcessor {
var books: () -> Array<Any>
}
For more complicated structures it can easily become a challenge.
Here's what can be done to automate such translations.
You can:
generate typescript declaration for this code with typescript compiler (using tsc -d)
generate kotlin declaration with dukat.
Dukat is a tool from Kotlin/JS team created specifically for this, there's ongoing battle for improving the quality of this tool. Here is what would be generated in your particular case:
external interface `T$0` {
var books: () -> Array<Any>
}
external interface `T$1` {
var Query: `T$0`
}
external object config {
var defs: String
var resolvers: `T$1`
}
Which is far from optimal - for instance the name of generated entities is something we didn't wanted to encourage people to reuse but the more it goes, the more it looks like a mistake (which we will fix this way or another).
Is it possible to find all kotlin classes in a given package?
I also need only annotated classes but it's not a big deal. Any suggestions ?
Kotlin on the JVM suffers the same issue as Java in this regard due to the implementation of class loaders.
Class loaders are not required to tell the VM which classes it can provide, instead they are just handed requests for classes, and have to return a class or throw an exception.
Source and more information: Can you find all classes in a package using reflection?
To summarize the linked thread, there are a number of solutions that allow you to inspect your current class path.
The Reflections library is pretty straight forward and has a lot of additional functionality like getting all subtypes of a class, get all types/members annotated with some annotation, optionally with annotation parameters matching, etc.
Guava has ClassPath, which returns ClassInfo POJO's - not enough for your use case, but useful to know as Guava is available almost everywhere.
Write your own by querying classloader resources and code sources. Would not suggest this route unless you absolutely cannot add library dependencies.
Here's an example of querying classloader resources, adapted from https://www.javaworld.com/article/2077477/java-tip-113--identify-subclasses-at-runtime.html
Requires Java 8 or higher.
// Call this function using something like:
// findClasses("com.mypackage.mysubpackage")
// Modified from https://www.javaworld.com/article/2077477/java-tip-113--identify-subclasses-at-runtime.html
fun findClasses(pckgname: String) {
// Translate the package name into an absolute path
var name = pckgname
if (!name.startsWith("/")) {
name = "/$name"
}
name = name.replace('.', '/')
// Get a File object for the package
val url: URL = Launcher::class.java.getResource(name)
val directory = File(url.getFile())
println("Finding classes:")
if (directory.exists()) {
// Get the list of the files contained in the package
directory.walk()
.filter { f -> f.isFile() && f.name.contains('$') == false && f.name.endsWith(".class") }
.forEach {
val fullyQualifiedClassName = pckgname +
it.canonicalPath.removePrefix(directory.canonicalPath)
.dropLast(6) // remove .class
.replace('/', '.')
try {
// Try to create an instance of the object
val o = Class.forName(fullyQualifiedClassName).getDeclaredConstructor().newInstance()
if (o is MyInterfaceOrClass) {
println(fullyQualifiedClassName)
// Optionally, make a function call here: o.myFunction()
}
} catch (cnfex: ClassNotFoundException) {
System.err.println(cnfex)
} catch (iex: InstantiationException) {
// We try to instantiate an interface
// or an object that does not have a
// default constructor
} catch (iaex: IllegalAccessException) {
// The class is not public
}
}
}
}