Merge pull request #11033 from smoogipoo/immutable-hit-samples

Make HitSampleInfo immutable

osu.Game.Rulesets.Catch.Tests/TestSceneAutoJuiceStream.cs

@@ -43,7 +43,7 @@ namespace osu.Game.Rulesets.Catch.Tests
                     NewCombo = i % 8 == 0,
                     Samples = new List<HitSampleInfo>(new[]
                     {
-                        new HitSampleInfo { Bank = "normal", Name = "hitnormal", Volume = 100 }
+                        new HitSampleInfo(HitSampleInfo.HIT_NORMAL, "normal", volume: 100)
                     })
                 });
             }

osu.Game.Rulesets.Catch/Objects/Banana.cs

@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using System.Collections.Generic;
 using osu.Framework.Utils;
 using osu.Game.Audio;
@@ -50,11 +51,24 @@ namespace osu.Game.Rulesets.Catch.Objects
             }
         }
 
-        private class BananaHitSampleInfo : HitSampleInfo
+        private class BananaHitSampleInfo : HitSampleInfo, IEquatable<BananaHitSampleInfo>
         {
-            private static string[] lookupNames { get; } = { "metronomelow", "catch-banana" };
+            private static readonly string[] lookup_names = { "metronomelow", "catch-banana" };
 
-            public override IEnumerable<string> LookupNames => lookupNames;
+            public override IEnumerable<string> LookupNames => lookup_names;
+
+            public BananaHitSampleInfo()
+                : base(string.Empty)
+            {
+            }
+
+            public bool Equals(BananaHitSampleInfo other)
+                => other != null;
+
+            public override bool Equals(object obj)
+                => obj is BananaHitSampleInfo other && Equals(other);
+
+            public override int GetHashCode() => lookup_names.GetHashCode();
         }
     }
 }

osu.Game.Rulesets.Catch/Objects/JuiceStream.cs

@@ -50,12 +50,7 @@ namespace osu.Game.Rulesets.Catch.Objects
         {
             base.CreateNestedHitObjects(cancellationToken);
 
-            var dropletSamples = Samples.Select(s => new HitSampleInfo
+            var dropletSamples = Samples.Select(s => s.With(@"slidertick")).ToList();
-            {
-                Bank = s.Bank,
-                Name = @"slidertick",
-                Volume = s.Volume
-            }).ToList();
 
             int nodeIndex = 0;
             SliderEventDescriptor? lastEvent = null;

osu.Game.Rulesets.Osu.Tests/TestSceneSlider.cs

@@ -108,8 +108,8 @@ namespace osu.Game.Rulesets.Osu.Tests
 
             AddStep("change samples", () => slider.HitObject.Samples = new[]
             {
-                new HitSampleInfo { Name = HitSampleInfo.HIT_CLAP },
+                new HitSampleInfo(HitSampleInfo.HIT_CLAP),
-                new HitSampleInfo { Name = HitSampleInfo.HIT_WHISTLE },
+                new HitSampleInfo(HitSampleInfo.HIT_WHISTLE),
             });
 
             AddAssert("head samples updated", () => assertSamples(slider.HitObject.HeadCircle));
@@ -136,15 +136,15 @@ namespace osu.Game.Rulesets.Osu.Tests
                 slider = (DrawableSlider)createSlider(repeats: 1);
 
                 for (int i = 0; i < 2; i++)
-                    slider.HitObject.NodeSamples.Add(new List<HitSampleInfo> { new HitSampleInfo { Name = HitSampleInfo.HIT_FINISH } });
+                    slider.HitObject.NodeSamples.Add(new List<HitSampleInfo> { new HitSampleInfo(HitSampleInfo.HIT_FINISH) });
 
                 Add(slider);
             });
 
             AddStep("change samples", () => slider.HitObject.Samples = new[]
             {
-                new HitSampleInfo { Name = HitSampleInfo.HIT_CLAP },
+                new HitSampleInfo(HitSampleInfo.HIT_CLAP),
-                new HitSampleInfo { Name = HitSampleInfo.HIT_WHISTLE },
+                new HitSampleInfo(HitSampleInfo.HIT_WHISTLE),
             });
 
             AddAssert("head samples not updated", () => assertSamples(slider.HitObject.HeadCircle));

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

@@ -115,8 +115,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 
             if (firstSample != null)
             {
-                var clone = HitObject.SampleControlPoint.ApplyTo(firstSample);
+                var clone = HitObject.SampleControlPoint.ApplyTo(firstSample).With("sliderslide");
-                clone.Name = "sliderslide";
 
                 samplesContainer.Add(slidingSample = new PausableSkinnableSound(clone)
                 {

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSpinner.cs

@@ -110,8 +110,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 
             if (firstSample != null)
             {
-                var clone = HitObject.SampleControlPoint.ApplyTo(firstSample);
+                var clone = HitObject.SampleControlPoint.ApplyTo(firstSample).With("spinnerspin");
-                clone.Name = "spinnerspin";
 
                 samplesContainer.Add(spinningSample = new PausableSkinnableSound(clone)
                 {

osu.Game.Rulesets.Osu/Objects/Slider.cs

@@ -221,14 +221,7 @@ namespace osu.Game.Rulesets.Osu.Objects
             var sampleList = new List<HitSampleInfo>();
 
             if (firstSample != null)
-            {
+                sampleList.Add(firstSample.With("slidertick"));
-                sampleList.Add(new HitSampleInfo
-                {
-                    Bank = firstSample.Bank,
-                    Volume = firstSample.Volume,
-                    Name = @"slidertick",
-                });
-            }
 
             foreach (var tick in NestedHitObjects.OfType<SliderTick>())
                 tick.Samples = sampleList;

osu.Game.Rulesets.Osu/Objects/SpinnerBonusTick.cs

@@ -11,7 +11,7 @@ namespace osu.Game.Rulesets.Osu.Objects
     {
         public SpinnerBonusTick()
         {
-            Samples.Add(new HitSampleInfo { Name = "spinnerbonus" });
+            Samples.Add(new HitSampleInfo("spinnerbonus"));
         }
 
         public override Judgement CreateJudgement() => new OsuSpinnerBonusTickJudgement();

osu.Game.Rulesets.Taiko/Objects/Drawables/DrawableHit.cs

@@ -79,7 +79,7 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
             if (isRimType != rimSamples.Any())
             {
                 if (isRimType)
-                    HitObject.Samples.Add(new HitSampleInfo { Name = HitSampleInfo.HIT_CLAP });
+                    HitObject.Samples.Add(new HitSampleInfo(HitSampleInfo.HIT_CLAP));
                 else
                 {
                     foreach (var sample in rimSamples)
@@ -125,9 +125,7 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
                     if (s.Name != HitSampleInfo.HIT_FINISH)
                         continue;
 
-                    var sClone = s.Clone();
+                    corrected[i] = s.With(HitSampleInfo.HIT_WHISTLE);
-                    sClone.Name = HitSampleInfo.HIT_WHISTLE;
-                    corrected[i] = sClone;
                 }
 
                 return corrected;

osu.Game.Rulesets.Taiko/Objects/Drawables/DrawableTaikoHitObject.cs

@@ -169,7 +169,7 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
             if (isStrong.Value != strongSamples.Any())
             {
                 if (isStrong.Value)
-                    HitObject.Samples.Add(new HitSampleInfo { Name = HitSampleInfo.HIT_FINISH });
+                    HitObject.Samples.Add(new HitSampleInfo(HitSampleInfo.HIT_FINISH));
                 else
                 {
                     foreach (var sample in strongSamples)

osu.Game.Tests/Editing/LegacyEditorBeatmapPatcherTest.cs

@@ -139,7 +139,7 @@ namespace osu.Game.Tests.Editing
                 HitObjects =
                 {
                     (OsuHitObject)current.HitObjects[0],
-                    new HitCircle { StartTime = 2000, Samples = { new HitSampleInfo { Name = HitSampleInfo.HIT_FINISH } } },
+                    new HitCircle { StartTime = 2000, Samples = { new HitSampleInfo(HitSampleInfo.HIT_FINISH) } },
                     (OsuHitObject)current.HitObjects[2],
                 }
             };
@@ -268,12 +268,12 @@ namespace osu.Game.Tests.Editing
                 HitObjects =
                 {
                     (OsuHitObject)current.HitObjects[0],
-                    new HitCircle { StartTime = 1000, Samples = { new HitSampleInfo { Name = HitSampleInfo.HIT_FINISH } } },
+                    new HitCircle { StartTime = 1000, Samples = { new HitSampleInfo(HitSampleInfo.HIT_FINISH) } },
                     (OsuHitObject)current.HitObjects[2],
                     (OsuHitObject)current.HitObjects[3],
-                    new HitCircle { StartTime = 2250, Samples = { new HitSampleInfo { Name = HitSampleInfo.HIT_WHISTLE } } },
+                    new HitCircle { StartTime = 2250, Samples = { new HitSampleInfo(HitSampleInfo.HIT_WHISTLE) } },
                     (OsuHitObject)current.HitObjects[5],
-                    new HitCircle { StartTime = 3000, Samples = { new HitSampleInfo { Name = HitSampleInfo.HIT_CLAP } } },
+                    new HitCircle { StartTime = 3000, Samples = { new HitSampleInfo(HitSampleInfo.HIT_CLAP) } },
                     (OsuHitObject)current.HitObjects[7],
                 }
             };

osu.Game/Audio/HitSampleInfo.cs

@@ -1,8 +1,12 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
+using Newtonsoft.Json;
+using osu.Game.Utils;
 
 namespace osu.Game.Audio
 {
@@ -10,7 +14,7 @@ namespace osu.Game.Audio
     /// Describes a gameplay hit sample.
     /// </summary>
     [Serializable]
-    public class HitSampleInfo : ISampleInfo
+    public class HitSampleInfo : ISampleInfo, IEquatable<HitSampleInfo>
     {
         public const string HIT_WHISTLE = @"hitwhistle";
         public const string HIT_FINISH = @"hitfinish";
@@ -22,29 +26,38 @@ namespace osu.Game.Audio
         /// </summary>
         public static IEnumerable<string> AllAdditions => new[] { HIT_WHISTLE, HIT_CLAP, HIT_FINISH };
 
-        /// <summary>
-        /// The bank to load the sample from.
-        /// </summary>
-        public string Bank;
-
         /// <summary>
         /// The name of the sample to load.
         /// </summary>
-        public string Name;
+        public readonly string Name;
+
+        /// <summary>
+        /// The bank to load the sample from.
+        /// </summary>
+        public readonly string? Bank;
 
         /// <summary>
         /// An optional suffix to provide priority lookup. Falls back to non-suffixed <see cref="Name"/>.
         /// </summary>
-        public string Suffix;
+        public readonly string? Suffix;
 
         /// <summary>
         /// The sample volume.
         /// </summary>
-        public int Volume { get; set; }
+        public int Volume { get; }
+
+        public HitSampleInfo(string name, string? bank = null, string? suffix = null, int volume = 0)
+        {
+            Name = name;
+            Bank = bank;
+            Suffix = suffix;
+            Volume = volume;
+        }
 
         /// <summary>
         /// Retrieve all possible filenames that can be used as a source, returned in order of preference (highest first).
         /// </summary>
+        [JsonIgnore]
         public virtual IEnumerable<string> LookupNames
         {
             get
@@ -56,6 +69,23 @@ namespace osu.Game.Audio
             }
         }
 
-        public HitSampleInfo Clone() => (HitSampleInfo)MemberwiseClone();
+        /// <summary>
+        /// Creates a new <see cref="HitSampleInfo"/> with overridden values.
+        /// </summary>
+        /// <param name="newName">An optional new sample name.</param>
+        /// <param name="newBank">An optional new sample bank.</param>
+        /// <param name="newSuffix">An optional new lookup suffix.</param>
+        /// <param name="newVolume">An optional new volume.</param>
+        /// <returns>The new <see cref="HitSampleInfo"/>.</returns>
+        public virtual HitSampleInfo With(Optional<string> newName = default, Optional<string?> newBank = default, Optional<string?> newSuffix = default, Optional<int> newVolume = default)
+            => new HitSampleInfo(newName.GetOr(Name), newBank.GetOr(Bank), newSuffix.GetOr(Suffix), newVolume.GetOr(Volume));
+
+        public bool Equals(HitSampleInfo? other)
+            => other != null && Name == other.Name && Bank == other.Bank && Suffix == other.Suffix;
+
+        public override bool Equals(object? obj)
+            => obj is HitSampleInfo other && Equals(other);
+
+        public override int GetHashCode() => HashCode.Combine(Name, Bank, Suffix);
     }
 }

osu.Game/Beatmaps/ControlPoints/SampleControlPoint.cs

@@ -58,12 +58,7 @@ namespace osu.Game.Beatmaps.ControlPoints
         /// </summary>
         /// <param name="sampleName">The name of the same.</param>
         /// <returns>A populated <see cref="HitSampleInfo"/>.</returns>
-        public HitSampleInfo GetSampleInfo(string sampleName = HitSampleInfo.HIT_NORMAL) => new HitSampleInfo
+        public HitSampleInfo GetSampleInfo(string sampleName = HitSampleInfo.HIT_NORMAL) => new HitSampleInfo(sampleName, SampleBank, volume: SampleVolume);
-        {
-            Bank = SampleBank,
-            Name = sampleName,
-            Volume = SampleVolume,
-        };
 
         /// <summary>
         /// Applies <see cref="SampleBank"/> and <see cref="SampleVolume"/> to a <see cref="HitSampleInfo"/> if necessary, returning the modified <see cref="HitSampleInfo"/>.
@@ -71,12 +66,7 @@ namespace osu.Game.Beatmaps.ControlPoints
         /// <param name="hitSampleInfo">The <see cref="HitSampleInfo"/>. This will not be modified.</param>
         /// <returns>The modified <see cref="HitSampleInfo"/>. This does not share a reference with <paramref name="hitSampleInfo"/>.</returns>
         public virtual HitSampleInfo ApplyTo(HitSampleInfo hitSampleInfo)
-        {
+            => hitSampleInfo.With(newBank: hitSampleInfo.Bank ?? SampleBank, newVolume: hitSampleInfo.Volume > 0 ? hitSampleInfo.Volume : SampleVolume);
-            var newSampleInfo = hitSampleInfo.Clone();
-            newSampleInfo.Bank = hitSampleInfo.Bank ?? SampleBank;
-            newSampleInfo.Volume = hitSampleInfo.Volume > 0 ? hitSampleInfo.Volume : SampleVolume;
-            return newSampleInfo;
-        }
 
         public override bool IsRedundant(ControlPoint existing)
             => existing is SampleControlPoint existingSample

osu.Game/Beatmaps/Formats/LegacyBeatmapEncoder.cs

@@ -192,7 +192,7 @@ namespace osu.Game.Beatmaps.Formats
                 var effectPoint = beatmap.ControlPointInfo.EffectPointAt(time);
 
                 // Apply the control point to a hit sample to uncover legacy properties (e.g. suffix)
-                HitSampleInfo tempHitSample = samplePoint.ApplyTo(new ConvertHitObjectParser.LegacyHitSampleInfo());
+                HitSampleInfo tempHitSample = samplePoint.ApplyTo(new ConvertHitObjectParser.LegacyHitSampleInfo(string.Empty));
 
                 // Convert effect flags to the legacy format
                 LegacyEffectFlags effectFlags = LegacyEffectFlags.None;

osu.Game/Beatmaps/Formats/LegacyDecoder.cs

@@ -182,11 +182,8 @@ namespace osu.Game.Beatmaps.Formats
             {
                 var baseInfo = base.ApplyTo(hitSampleInfo);
 
-                if (baseInfo is ConvertHitObjectParser.LegacyHitSampleInfo legacy
+                if (baseInfo is ConvertHitObjectParser.LegacyHitSampleInfo legacy && legacy.CustomSampleBank == 0)
-                    && legacy.CustomSampleBank == 0)
+                    return legacy.With(newCustomSampleBank: CustomSampleBank);
-                {
-                    legacy.CustomSampleBank = CustomSampleBank;
-                }
 
                 return baseInfo;
             }

osu.Game/Rulesets/Objects/Legacy/ConvertHitObjectParser.cs

@@ -13,6 +13,7 @@ using JetBrains.Annotations;
 using osu.Framework.Utils;
 using osu.Game.Beatmaps.Legacy;
 using osu.Game.Skinning;
+using osu.Game.Utils;
 
 namespace osu.Game.Rulesets.Objects.Legacy
 {
@@ -427,62 +428,25 @@ namespace osu.Game.Rulesets.Objects.Legacy
             // Todo: This should return the normal SampleInfos if the specified sample file isn't found, but that's a pretty edge-case scenario
             if (!string.IsNullOrEmpty(bankInfo.Filename))
             {
-                return new List<HitSampleInfo>
+                return new List<HitSampleInfo> { new FileHitSampleInfo(bankInfo.Filename, bankInfo.Volume) };
-                {
-                    new FileHitSampleInfo
-                    {
-                        Filename = bankInfo.Filename,
-                        Volume = bankInfo.Volume
-                    }
-                };
             }
 
             var soundTypes = new List<HitSampleInfo>
             {
-                new LegacyHitSampleInfo
+                new LegacyHitSampleInfo(HitSampleInfo.HIT_NORMAL, bankInfo.Normal, bankInfo.Volume, bankInfo.CustomSampleBank,
-                {
-                    Bank = bankInfo.Normal,
-                    Name = HitSampleInfo.HIT_NORMAL,
-                    Volume = bankInfo.Volume,
-                    CustomSampleBank = bankInfo.CustomSampleBank,
                     // if the sound type doesn't have the Normal flag set, attach it anyway as a layered sample.
                     // None also counts as a normal non-layered sample: https://osu.ppy.sh/help/wiki/osu!_File_Formats/Osu_(file_format)#hitsounds
-                    IsLayered = type != LegacyHitSoundType.None && !type.HasFlag(LegacyHitSoundType.Normal)
+                    type != LegacyHitSoundType.None && !type.HasFlag(LegacyHitSoundType.Normal))
-                }
             };
 
             if (type.HasFlag(LegacyHitSoundType.Finish))
-            {
+                soundTypes.Add(new LegacyHitSampleInfo(HitSampleInfo.HIT_FINISH, bankInfo.Add, bankInfo.Volume, bankInfo.CustomSampleBank));
-                soundTypes.Add(new LegacyHitSampleInfo
-                {
-                    Bank = bankInfo.Add,
-                    Name = HitSampleInfo.HIT_FINISH,
-                    Volume = bankInfo.Volume,
-                    CustomSampleBank = bankInfo.CustomSampleBank
-                });
-            }
 
             if (type.HasFlag(LegacyHitSoundType.Whistle))
-            {
+                soundTypes.Add(new LegacyHitSampleInfo(HitSampleInfo.HIT_WHISTLE, bankInfo.Add, bankInfo.Volume, bankInfo.CustomSampleBank));
-                soundTypes.Add(new LegacyHitSampleInfo
-                {
-                    Bank = bankInfo.Add,
-                    Name = HitSampleInfo.HIT_WHISTLE,
-                    Volume = bankInfo.Volume,
-                    CustomSampleBank = bankInfo.CustomSampleBank
-                });
-            }
 
             if (type.HasFlag(LegacyHitSoundType.Clap))
-            {
+                soundTypes.Add(new LegacyHitSampleInfo(HitSampleInfo.HIT_CLAP, bankInfo.Add, bankInfo.Volume, bankInfo.CustomSampleBank));
-                soundTypes.Add(new LegacyHitSampleInfo
-                {
-                    Bank = bankInfo.Add,
-                    Name = HitSampleInfo.HIT_CLAP,
-                    Volume = bankInfo.Volume,
-                    CustomSampleBank = bankInfo.CustomSampleBank
-                });
-            }
 
             return soundTypes;
         }
@@ -500,21 +464,11 @@ namespace osu.Game.Rulesets.Objects.Legacy
             public SampleBankInfo Clone() => (SampleBankInfo)MemberwiseClone();
         }
 
-        public class LegacyHitSampleInfo : HitSampleInfo
+#nullable enable
+
+        public class LegacyHitSampleInfo : HitSampleInfo, IEquatable<LegacyHitSampleInfo>
         {
-            private int customSampleBank;
+            public readonly int CustomSampleBank;
-
-            public int CustomSampleBank
-            {
-                get => customSampleBank;
-                set
-                {
-                    customSampleBank = value;
-
-                    if (value >= 2)
-                        Suffix = value.ToString();
-                }
-            }
 
             /// <summary>
             /// Whether this hit sample is layered.
@@ -523,18 +477,41 @@ namespace osu.Game.Rulesets.Objects.Legacy
             /// Layered hit samples are automatically added in all modes (except osu!mania), but can be disabled
             /// using the <see cref="LegacySkinConfiguration.LegacySetting.LayeredHitSounds"/> skin config option.
             /// </remarks>
-            public bool IsLayered { get; set; }
+            public readonly bool IsLayered;
+
+            public LegacyHitSampleInfo(string name, string? bank = null, int volume = 0, int customSampleBank = 0, bool isLayered = false)
+                : base(name, bank, customSampleBank >= 2 ? customSampleBank.ToString() : null, volume)
+            {
+                CustomSampleBank = customSampleBank;
+                IsLayered = isLayered;
+            }
+
+            public sealed override HitSampleInfo With(Optional<string> newName = default, Optional<string?> newBank = default, Optional<string?> newSuffix = default, Optional<int> newVolume = default)
+                => With(newName, newBank, newVolume);
+
+            public virtual LegacyHitSampleInfo With(Optional<string> newName = default, Optional<string?> newBank = default, Optional<int> newVolume = default, Optional<int> newCustomSampleBank = default,
+                                                    Optional<bool> newIsLayered = default)
+                => new LegacyHitSampleInfo(newName.GetOr(Name), newBank.GetOr(Bank), newVolume.GetOr(Volume), newCustomSampleBank.GetOr(CustomSampleBank), newIsLayered.GetOr(IsLayered));
+
+            public bool Equals(LegacyHitSampleInfo? other)
+                => base.Equals(other) && CustomSampleBank == other.CustomSampleBank && IsLayered == other.IsLayered;
+
+            public override bool Equals(object? obj)
+                => obj is LegacyHitSampleInfo other && Equals(other);
+
+            public override int GetHashCode() => HashCode.Combine(base.GetHashCode(), CustomSampleBank, IsLayered);
         }
 
-        private class FileHitSampleInfo : LegacyHitSampleInfo
+        private class FileHitSampleInfo : LegacyHitSampleInfo, IEquatable<FileHitSampleInfo>
         {
-            public string Filename;
+            public readonly string Filename;
 
-            public FileHitSampleInfo()
+            public FileHitSampleInfo(string filename, int volume)
-            {
+                // Force CSS=1 to make sure that the LegacyBeatmapSkin does not fall back to the user skin.
-                // Make sure that the LegacyBeatmapSkin does not fall back to the user skin.
                 // Note that this does not change the lookup names, as they are overridden locally.
-                CustomSampleBank = 1;
+                : base(string.Empty, customSampleBank: 1, volume: volume)
+            {
+                Filename = filename;
             }
 
             public override IEnumerable<string> LookupNames => new[]
@@ -542,6 +519,20 @@ namespace osu.Game.Rulesets.Objects.Legacy
                 Filename,
                 Path.ChangeExtension(Filename, null)
             };
+
+            public sealed override LegacyHitSampleInfo With(Optional<string> newName = default, Optional<string?> newBank = default, Optional<int> newVolume = default, Optional<int> newCustomSampleBank = default,
+                                                            Optional<bool> newIsLayered = default)
+                => new FileHitSampleInfo(Filename, newVolume.GetOr(Volume));
+
+            public bool Equals(FileHitSampleInfo? other)
+                => base.Equals(other) && Filename == other.Filename;
+
+            public override bool Equals(object? obj)
+                => obj is FileHitSampleInfo other && Equals(other);
+
+            public override int GetHashCode() => HashCode.Combine(base.GetHashCode(), Filename);
         }
+
+#nullable disable
     }
 }

osu.Game/Screens/Edit/Compose/Components/ComposeBlueprintContainer.cs

@@ -101,7 +101,7 @@ namespace osu.Game.Screens.Edit.Compose.Components
 
                 case TernaryState.True:
                     if (existingSample == null)
-                        samples.Add(new HitSampleInfo { Name = sampleName });
+                        samples.Add(new HitSampleInfo(sampleName));
                     break;
             }
         }
@@ -212,7 +212,7 @@ namespace osu.Game.Screens.Edit.Compose.Components
             if (blueprint != null)
             {
                 // doing this post-creations as adding the default hit sample should be the case regardless of the ruleset.
-                blueprint.HitObject.Samples.Add(new HitSampleInfo { Name = HitSampleInfo.HIT_NORMAL });
+                blueprint.HitObject.Samples.Add(new HitSampleInfo(HitSampleInfo.HIT_NORMAL));
 
                 placementBlueprintContainer.Child = currentPlacement = blueprint;
 

osu.Game/Screens/Edit/Compose/Components/SelectionHandler.cs

@@ -328,7 +328,7 @@ namespace osu.Game.Screens.Edit.Compose.Components
                 if (h.Samples.Any(s => s.Name == sampleName))
                     continue;
 
-                h.Samples.Add(new HitSampleInfo { Name = sampleName });
+                h.Samples.Add(new HitSampleInfo(sampleName));
             }
 
             EditorBeatmap.EndChange();

osu.Game/Utils/Optional.cs

@@ -0,0 +1,45 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+#nullable enable
+
+namespace osu.Game.Utils
+{
+    /// <summary>
+    /// A wrapper over a value and a boolean denoting whether the value is valid.
+    /// </summary>
+    /// <typeparam name="T">The type of value stored.</typeparam>
+    public readonly ref struct Optional<T>
+    {
+        /// <summary>
+        /// The stored value.
+        /// </summary>
+        public readonly T Value;
+
+        /// <summary>
+        /// Whether <see cref="Value"/> is valid.
+        /// </summary>
+        /// <remarks>
+        /// If <typeparamref name="T"/> is a reference type, <c>null</c> may be valid for <see cref="Value"/>.
+        /// </remarks>
+        public readonly bool HasValue;
+
+        private Optional(T value)
+        {
+            Value = value;
+            HasValue = true;
+        }
+
+        /// <summary>
+        /// Returns <see cref="Value"/> if it's valid, or a given fallback value otherwise.
+        /// </summary>
+        /// <remarks>
+        /// Shortcase for: <c>optional.HasValue ? optional.Value : fallback</c>.
+        /// </remarks>
+        /// <param name="fallback">The fallback value to return if <see cref="HasValue"/> is <c>false</c>.</param>
+        /// <returns></returns>
+        public T GetOr(T fallback) => HasValue ? Value : fallback;
+
+        public static implicit operator Optional<T>(T value) => new Optional<T>(value);
+    }
+}