From 5820696126f4d3b959f66157d5fc36d1d0d66c5b Mon Sep 17 00:00:00 2001
From: Lukas Rytz <lukas.rytz@gmail.com>
Date: Fri, 26 May 2023 11:45:04 +0200
Subject: [PATCH 1/2] Early init migration for another common use case

---
 .../incompat-dropped-features.md              | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/_overviews/scala3-migration/incompat-dropped-features.md b/_overviews/scala3-migration/incompat-dropped-features.md
index 4d5b2d5d7..03b4d35f8 100644
--- a/_overviews/scala3-migration/incompat-dropped-features.md
+++ b/_overviews/scala3-migration/incompat-dropped-features.md
@@ -226,6 +226,45 @@ class Fizz private (val name: String) extends Bar {
 {% endtab %}
 {% endtabs %}
 
+Another use case for early initializers in Scala 2 is private state in the subclass that is accessed (through an overridden method) by the constructor of the superclass:
+
+{% tabs scala-2-initializer_5 %}
+{% tab 'Scala 2 Only' %}
+~~~ scala
+class Adder {
+  var sum = 0
+  def add(x: Int): Unit = sum += x
+  add(1)
+}
+class LogAdder extends Adder {
+  private var added: Set[Int] = Set.empty
+  override def add(x: Int): Unit = { added += x; super.add(x) }
+}
+~~~
+{% endtab %}
+{% endtabs %}
+
+This case can be refactored by moving the private state into a nested `object`, which is initialized on demand:
+
+{% tabs shared-initializer_6 %}
+{% tab 'Scala 2 and 3' %}
+~~~ scala
+class Adder {
+  var sum = 0
+  def add(x: Int): Unit = sum += x
+  add(1)
+}
+class LogAdder extends Adder {
+  private object state {
+    var added: Set[Int] = Set.empty
+  }
+  import state._
+  override def add(x: Int): Unit = { added += x; super.add(x) }
+}
+~~~
+{% endtab %}
+{% endtabs %}
+
 ## Existential Type
 
 Existential type is a [dropped feature]({{ site.scala3ref }}/dropped-features/existential-types.html), which makes the following code invalid.

From bc4c407e8ed348389967ab36ebef6b4c9a966f87 Mon Sep 17 00:00:00 2001
From: Lukas Rytz <lukas.rytz@gmail.com>
Date: Fri, 26 May 2023 12:09:03 +0200
Subject: [PATCH 2/2] Update
 _overviews/scala3-migration/incompat-dropped-features.md
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Sébastien Doeraene <sjrdoeraene@gmail.com>
---
 _overviews/scala3-migration/incompat-dropped-features.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/_overviews/scala3-migration/incompat-dropped-features.md b/_overviews/scala3-migration/incompat-dropped-features.md
index 03b4d35f8..afdbe0022 100644
--- a/_overviews/scala3-migration/incompat-dropped-features.md
+++ b/_overviews/scala3-migration/incompat-dropped-features.md
@@ -236,8 +236,9 @@ class Adder {
   def add(x: Int): Unit = sum += x
   add(1)
 }
-class LogAdder extends Adder {
+class LogAdder extends {
   private var added: Set[Int] = Set.empty
+} with Adder {
   override def add(x: Int): Unit = { added += x; super.add(x) }
 }
 ~~~