Merge pull request #4 from vjames19/mapError

preferring the reified version of mapError
vjames19 · Jul 11, 2017 · 176667f · 176667f
2 parents 1a94b97 + 52daad8
commit 176667f
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diff --git a/README.md b/README.md
@@ -298,7 +298,7 @@ mapError allows you only to transform the error types you are interested
 import io.github.vjames19.futures.jdk8.*
 
 val failed = Future<String> { throw IllegalArgumentException() }
-        .mapError(IllegalArgumentException::class) {
+        .mapError { e: IllegalArgumentException ->
             // handle the IllegalArgumentException here and return a more pertinent exception
         }
 ```

diff --git a/kotlin-futures-jdk8/src/main/kotlin/io/github/vjames19/futures/jdk8/CompletableFutureExt.kt b/kotlin-futures-jdk8/src/main/kotlin/io/github/vjames19/futures/jdk8/CompletableFutureExt.kt
@@ -8,7 +8,6 @@ import java.util.function.BiConsumer
 import java.util.function.BiFunction
 import java.util.function.Function
 import java.util.function.Supplier
-import kotlin.reflect.KClass
 
 // Creation
 inline fun <A> Future(executor: Executor = ForkJoinExecutor, crossinline block: () -> A): CompletableFuture<A> =
@@ -52,10 +51,10 @@ inline fun <A> CompletableFuture<A>.recoverWith(executor: Executor = ForkJoinExe
     return future
 }
 
-inline fun <A, E : Throwable> CompletableFuture<A>.mapError(clazz: KClass<E>, crossinline f: (E) -> Throwable): CompletableFuture<A> = exceptionally {
+inline fun <A, reified E : Throwable> CompletableFuture<A>.mapError(crossinline f: (E) -> Throwable): CompletableFuture<A> = exceptionally {
     val throwable = it.cause ?: it
-    if (clazz.isInstance(throwable)) {
-        throw f(clazz.java.cast(throwable))
+    if (throwable is E) {
+        throw f(throwable)
     } else {
         throw throwable
     }

diff --git a/kotlin-futures-jdk8/src/test/kotlin/io/github/vjames19/futures/jdk8/FutureSpec.kt b/kotlin-futures-jdk8/src/test/kotlin/io/github/vjames19/futures/jdk8/FutureSpec.kt
@@ -115,26 +115,26 @@ object FutureSpec : Spek({
     describe("mapError") {
         given("a successful future") {
             it("it shouldn't have to map the error") {
-                success.mapError(IllegalArgumentException::class) { IllegalStateException() }.get() shouldEqual 1
+                success.mapError { _: IllegalArgumentException -> IllegalStateException() }.get() shouldEqual 1
             }
         }
 
         given("a failed future") {
             on("an exception type that its willing to handle") {
                 it("should map the error") {
-                    { failed.mapError(IllegalArgumentException::class) { UnsupportedOperationException() }.get() } shouldThrowTheException AnyException withCause (UnsupportedOperationException::class)
+                    { failed.mapError { _: IllegalArgumentException -> UnsupportedOperationException() }.get() } shouldThrowTheException AnyException withCause (UnsupportedOperationException::class)
                 }
             }
 
             on("an exception type that it didn't register for") {
                 it("should throw the original error") {
-                    { failed.mapError(IllegalStateException::class) { UnsupportedOperationException() }.get() } shouldThrowTheException AnyException withCause (IllegalArgumentException::class)
+                    { failed.mapError { _: ClassNotFoundException -> UnsupportedOperationException() }.get() } shouldThrowTheException AnyException withCause (IllegalArgumentException::class)
                 }
             }
 
             on("handling the supertype Throwable") {
                 it("should map the error") {
-                    { failed.mapError(Throwable::class) { UnsupportedOperationException() }.get() } shouldThrowTheException AnyException withCause (UnsupportedOperationException::class)
+                    { failed.mapError { _: Throwable -> UnsupportedOperationException() }.get() } shouldThrowTheException AnyException withCause (UnsupportedOperationException::class)
                 }
             }
         }