From de32e7815b19d8ea5a19114eebc67d3f85ecaa27 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Mon, 29 Jan 2024 14:57:19 +0900
Subject: [PATCH] Clean up `DrawableHitObject` events on `Dispose`

This is just general safeties to avoid cases where
components don't correctly unbind events.
---
 osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs | 7 +++++++
 osu.Game/Rulesets/Objects/HitObject.cs                   | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs b/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs
index bce28361cb..5662fb2293 100644
--- a/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs
+++ b/osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs
@@ -768,6 +768,13 @@ namespace osu.Game.Rulesets.Objects.Drawables
 
             if (CurrentSkin != null)
                 CurrentSkin.SourceChanged -= skinSourceChanged;
+
+            // Safeties against shooting in foot in cases where these are bound by external entities (like playfield) that don't clean up.
+            OnNestedDrawableCreated = null;
+            OnNewResult = null;
+            OnRevertResult = null;
+            DefaultsApplied = null;
+            HitObjectApplied = null;
         }
 
         public Bindable<double> AnimationStartTime { get; } = new BindableDouble();
diff --git a/osu.Game/Rulesets/Objects/HitObject.cs b/osu.Game/Rulesets/Objects/HitObject.cs
index ec2a4a31f6..ef8bd08bf4 100644
--- a/osu.Game/Rulesets/Objects/HitObject.cs
+++ b/osu.Game/Rulesets/Objects/HitObject.cs
@@ -38,6 +38,8 @@ namespace osu.Game.Rulesets.Objects
         /// <summary>
         /// Invoked after <see cref="ApplyDefaults"/> has completed on this <see cref="HitObject"/>.
         /// </summary>
+        // TODO: This has no implicit unbind flow. Currently, if a Playfield manages HitObjects it will leave a bound event on this and cause the
+        // playfield to remain in memory.
         public event Action<HitObject> DefaultsApplied;
 
         public readonly Bindable<double> StartTimeBindable = new BindableDouble();