Foreach 泛型作为特定类型答案

【问题标题】：Foreach generic as specific typeForeach 泛型作为特定类型
【发布时间】：2022-08-14 03:53:42
【问题描述】：

无法解决并找到解决方案。我想创建易于扩展的结构并将数据保存到 ScriptableObjects。例如，我根据 SettingsSO 创建了 2 个 AudioSettings（资产）：DefaultSettings、CurrentSettings，然后我将在 UnityEditor 上设置 Default 并存储用户的设置在 Current 中，如果 Current == null 则 Current = CreateInstance<Default>。所以任何设置组都有2个参考。将来我想在 SettingManager 中添加另一个设置组，并能够将它们全部添加到某个列表或字典中，然后 foreach 做一些常见的事情。例如加载默认设置。

设置管理器.cs

public class SettingsManager
{
    [SerializeField] private SettingGroup<VideoSettings> _videoSettings;
    [SerializeField] private SettingGroup<AudioSettings> _audioSettings;

    private Dictionary<Type, SettingGroup> _settingDictionary;

    public void Init()
    {
        _settingDictionary = new Dictionary<Type, SettingGroup>
        {
            { _audioSettings.GetType(), _audioSettings },
            { _videoSettings.GetType(), _videoSettings }
        };
    }

    private void LoadDefaultSetting()
    {
        foreach (var pair in _settingDictionary)
        {
            //var eachSettingGroup = (pair.Key)pair.Value;              //Error Cannot resolve symbol \'pair\'
            //var eachSettingGroup = pair.Value as pair.Key;            //Error Cannot resolve symbol \'pair\'
            //var eachSettingGroup = (typeof(pair.Key))pair.Value;    //Error Cannot resolve symbol \'pair\'
            var eachSettingGroup = I need settings.Default HelpMeGuys!! (;
            eachSettingGroup.Init();
        }
    }
}

设置组.cs

public class SettingGroup<T> : SettingGroup where T : SettingsSO
    {
        public T Default => _default;
        public T Current => _current;
        public Type SettingsType => typeof(T);


        [SerializeField] private T _default;
        [SerializeField] private T _current;
        private T _lastSaved;

        public void Init()
        {
            if (_current == null)
            {
                Debug.LogWarning(\"Current settings reference not found. Default settings using instead without saving.\");
                _current = ScriptableObject.CreateInstance<T>();
                _default.CopyDataTo(_current);
            }

            _lastSaved = ScriptableObject.CreateInstance<T>();
            _current.CopyDataTo(_lastSaved);
        }
    }

音频设置.cs

public class AudioSettings : SettingsSO
{
   public bool MusicEnabled;
   public bool SoundEnabled;
   public float MusicVolume;
   public float SoundVolume;
}

设置SO.cs

public abstract class SettingsSO : ScriptableObject
{
    public string Description;
}

SettingGroup 中似乎没有 Default，对于实际的类型转换，您需要在编译时定义类型，它不能是运行时值。您可能会尝试使用反射来做一些事情，尽管我不确定 Unity 是否支持所有平台上的反射
你只是想迭代你的字典却不知道怎么做？
至于我，您可以在 SettingsSO 方法中创建，命名为 \"GetDefaultSetting\" 并在音频和视频设置中覆盖此方法

标签： c# unity3d generics scriptable-object

【解决方案1】：

有点不清楚您的SettingGroup<T> 需要哪些功能，以及SettingGroup 中是否有任何重要的东西，我们看不到。但是您可以通过引入带有covariant generic type 的接口来解决眼前的问题：

// Notice the 'out' keyword    vvv
public interface ISettingGroup<out T> where T : SettingsSO
{
    public T Default { get; }
    public T Current { get; }
    public Type SettingsType { get; }
    
    public void Init();
}

然后在您的SettingGroup 中实现该接口：

public class SettingGroup<T> : ISettingGroup<T> where T : SettingsSO
{ /* ... */ }

在您的SettingsManager 中，我们现在可以更改字典值的类型：

public class SettingsManager
{
    [SerializeField] private SettingGroup<VideoSettings> _videoSettings;
    [SerializeField] private SettingGroup<AudioSettings> _audioSettings;

    // Now uses the interface vvvvvvvvvvvvvvvvvvvvvvv
    private Dictionary<Type,  ISettingGroup<SettingsSO>> _settingDictionary;

    public void Init()
    {
        _settingDictionary = new Dictionary<Type, SettingGroup>
        {
            { _audioSettings.GetType(), _audioSettings },
            { _videoSettings.GetType(), _videoSettings }
        };
    }

    private void LoadDefaultSetting()
    {
        foreach (var pair in _settingDictionary)
        {
            // No need for any type casting now...
            var settingGroup = pair.Value;
            var settingsDefault = settingGroup.Default;
            settingGroup.Init();
        }
    }
}

【讨论】：

【解决方案2】：

我找到了解决方案，我忘记了那些设置组将使用相同的方法，我可以将这些方法替换为接口。而且我不需要知道这是设置组的哪种类型。

设置组.cs

    public interface SettingGroup
    {
        void Init();
    }

    [Serializable]
    public class SettingGroup<T> : SettingGroup where T : SettingsSO
    {
        [SerializeField] private T _default;
        [SerializeField] private T _saved;
        [SerializeField] private T _current;

        public T CurrentSettings  => _current;

        public void Init()
        {
            if (_saved == null)
            {
                Debug.LogWarning(
                    "Current settings reference not found. Default settings using instead without saving.");
                _saved = ScriptableObject.CreateInstance<T>();
                _saved.CopyDataFrom(_default);
            }

            _current = ScriptableObject.CreateInstance<T>();
            _current.CopyDataFrom(_saved);
        }
    }
}

设置管理器.cs

    [Serializable]
    public class SettingsManager
    {
        [SerializeField] private SettingGroup<VideoSettings> _videoSettings;
        [SerializeField] private SettingGroup<AudioSettings> _audioSettings;

        public VideoSettings Video => _videoSettings.CurrentSettings;
        public AudioSettings Audio => _audioSettings.CurrentSettings;

        private List<SettingGroup> _settingList;

        public void Init()
        {
            //TODO don't forget to add all above SettingsGroups to list 
            _settingList = new List<SettingGroup>
            {
                _audioSettings, 
                _videoSettings
            };

            foreach (var settingGroup in _settingList)
            {
                settingGroup.Init();
            }
        }
   }

【讨论】：