Merge pull request #2231 from satorg/make-derived-final

Mark `class Derived` as `final`

Author: jatcwang

modules/core/src/main/scala/doobie/util/Derived.scala renamed to modules/core/src/main/scala-2/doobie/util/Derived.scala

@@ -4,4 +4,4 @@
 
 package doobie.util
 
-class Derived[+I](val instance: I) extends AnyVal
+final class Derived[+I](val instance: I) extends AnyVal

modules/core/src/main/scala-3/doobie/util/Derived.scala

@@ -0,0 +1,13 @@
+// Copyright (c) 2013-2020 Rob Norris and Contributors
+// This software is licensed under the MIT License (MIT).
+// For more information see LICENSE or https://opensource.org/licenses/MIT
+
+package doobie.util
+
+opaque type Derived[+I] = I
+
+object Derived:
+  def apply[I](i: I): Derived[I] = i
+
+extension [I](d: Derived[I])
+  def instance: I = d

modules/core/src/main/scala-3/doobie/util/MkReadPlatform.scala

@@ -20,16 +20,16 @@ trait MkReadPlatform:
   ): Derived[MkRead[P]] = {
     val _ = isNotCaseObj
     val read = r.fold(identity, _.instance).map(a => m.fromProduct(i(a)))
-    new Derived(new MkRead(read))
+    Derived(new MkRead(read))
   }
 
   // Derivation base case for tuple (1-element)
   implicit def productBase[H](
       implicit H: Read[H] `OrElse` Derived[MkRead[H]]
   ): Derived[MkRead[H *: EmptyTuple]] = {
     val headInstance = H.fold(identity, _.instance)
-    new Derived(
-      new MkRead(
+    Derived(
+      MkRead(
         Read.Transform(
           headInstance,
           h => h *: EmptyTuple
@@ -46,8 +46,8 @@ trait MkReadPlatform:
     val headInstance = H.fold(identity, _.instance)
     val tailInstance = T.fold(identity, _.instance)
 
-    new Derived(
-      new MkRead(
+    Derived(
+      MkRead(
         Read.Composite(
           headInstance,
           tailInstance,

modules/core/src/main/scala-3/doobie/util/MkWritePlatform.scala

@@ -20,17 +20,17 @@ trait MkWritePlatform:
   ): Derived[MkWrite[P]] =
     val _ = isNotCaseObj
     val write: Write[P] = w.fold(identity, _.instance).contramap(p => i(Tuple.fromProductTyped(p)))
-    new Derived(
-      new MkWrite(write)
+    Derived(
+      MkWrite(write)
     )
 
   // Derivation base case for tuple (1-element)
   implicit def productBase[H](
       implicit H: Write[H] `OrElse` Derived[MkWrite[H]]
   ): Derived[MkWrite[H *: EmptyTuple]] = {
     val headInstance = H.fold(identity, _.instance)
-    new Derived(
-      new MkWrite(Write.Composite(
+    Derived(
+      MkWrite(Write.Composite(
         List(headInstance),
         { case h *: EmptyTuple =>
           List(h)
@@ -48,8 +48,8 @@ trait MkWritePlatform:
     val headWrite = H.fold(identity, _.instance)
     val tailWrite = T.fold(identity, _.instance)
 
-    new Derived(
-      new MkWrite(Write.Composite(
+    Derived(
+      MkWrite(Write.Composite(
         List(headWrite, tailWrite),
         { case h *: t =>
           List(h, t)