kotlin-cast
0.0.1indexedEnhances casting functionality by providing polyfills for safely casting instances, enabling type inference without disrupting typing flow, even for non-public functions.
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kotlin-cast
kotlin-cast is a polyfill for 3 functions that help you cast your Kotlin instances without going back in your typing flow:
inline fun <reified T : Any> Any?.safeAs(): T? = this as? T
inline fun <reified T : Any> Any?.cast(): T = this as T
inline fun <reified T : Any> Any?.assertedCast(message: () -> String): T = this as? T ?: throw AssertionError(message())
Import in your project:
[libraries]
cast = "net.mbonnin.cast:cast:0.0.1"
Usage:
val data: Any? = jsonToKotlin("{\"key\": \"value\"}")
val value = data.cast<Map<String, Any?>>()
.get("key")
.cast<String>() // YAYYYYY!!!
assertEquals("value", value)
Using type inference makes it even shorter:
fun doStuff(foo: Foo) { ... }
val any: Any = TODO()
doStuff(any.cast()) // cast to Foo automatically
Those functions are part of the kotlin-stdlib but not public, mainly because they break some diagnostics:
val a = "Hello"
val b: Int = a as Int // IJ will tell you "this cast can never succeed"
val c: Int = a.cast<Int>() // You'll get a crash without a warning.
Learn more in KT-8584.