Unity C#使用委托创建可观察变量

Question

我要做的事情：

ScriptableObject类，用于保存单个变量，该变量可以在观察者模式中订阅，以便在值更改时接收通知。

我的意图是当UI显示的内容发生变化时进行更新，而不必在每次更改时手动触发事件。

此外，我希望我的课有三个功能：

1. 使用try/catch来真正解耦事物，而不是因为一个侦听器失败就让所有侦听器失败
2. 可以选择记录调试内容
3. 显示检查器中当前活动的观察者的列表

我以为这是Delegate的几行代码，但事实证明没有，这根本不起作用。

我第一次天真的迭代是：

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

[CreateAssetMenu(fileName = "New Observable Float", menuName = "Observables/Float")]
public class ObservableFloat : ScriptableObject {
public event Action<float> get;
[SerializeField] private float m_Value;
public float Value {
get {
return m_Value;
}
set {
m_Value = value;
get?.Invoke(value);
}
}
}

我的第二次迭代在功能上起作用，但没有向我显示检查器中的观察者列表，它是这样的：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

[CreateAssetMenu(fileName = "New Observable Float", menuName = "Observables/Float")]
public class ObservableFloat : ScriptableObject {
[SerializeField] List<UnityAction<float>> listeners = new List<UnityAction<float>>();
[SerializeField] private float m_Value;
public float Value {
get {
return m_Value;
}
set {
m_Value = value;
foreach (UnityAction<float> action in listeners) {
action.Invoke(value);
}
}
}
public void AddListener(UnityAction<float> func) => listeners.Add(func);
public void RemoveListener(UnityAction<float> func) => listeners.Remove(func);
}

我的第三次迭代，用UnityEvents替换UnityAction，乍一看似乎有效(列表显示在Inspector中(，但它从不更新列表，并且总是显示为空，尽管在功能上它也有效：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using Sirenix.OdinInspector;

[CreateAssetMenu(fileName = "New Observable Float", menuName = "Observables/Float")]
public class ObservableFloat : ScriptableObject {
public UnityEvent<float> listeners = new UnityEvent<float>();
[SerializeField] private float m_Value;
public float Value {
get {
return m_Value;
}
set {
m_Value = value;
listeners?.Invoke(value);
}
}
}

Answer 1

一般来说，我认为您想要的是UnityEvent

[SerializeField] private UnityEvent<float> listeners;
public void AddListener(Action<float> action) => listeners.AddListener(action);
public void  RemoveListener(Action<float> action) => listeners.RemoveListener(action);
[SerializeField] private float m_Value;
public float Value {
get {
return m_Value;
}
set {
m_Value = value;
listeners?.Invoke(value);
}
}

不幸的是，这些总是只显示Inspector中的持久侦听器。没有简单的内置方式也可以显示运行时回调，如果你想这样做，我想没有办法绕过反射和/或非常复杂的特殊Inspector实现。

例如，你可以存储之类的东西

using System.Reflection;
using System.Linq;
...
[Serializable]
public class ListenerInfo
{
public Action<float> action;
public string MethodName;
public string TypeName;
}
[SerializeField] private List<string> listenerInfos;
public void AddListener(Action<float> action)
{
listeners.AddListener(action);
var info = action.GetMethodInfo();
listenerInfos.Add(new ListenerInfo { action = action, MethodName = info.Name, TypeName = info.DeclaringType.Name });
}
public void RemoveListener (Action<float> action)
{
listeners.RemoveListener(action);
var info = var info = action.GetMethodInfo();
listenerInfos.RemoveAll(l => l.action == action);
}

另请参见例如Action delegate。如何获取调用方法的实例

我想这将是最接近你所能得到的，而不需要真正深入到Unity Editor脚本和更多的反思^^

Answer 2

我已经提出了一个可行的解决方案，尽管我对此并不完全确定，所以我在CodeReview中发布了它-https://codereview.stackexchange.com/questions/272241/unity3d-observable-variable

以下是代码(但请查看上面的链接以了解可能的修复/改进(。非常感谢@derHugo，他为我指明了正确的方向：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using UnityEditor;
using Sirenix.OdinInspector;

[CreateAssetMenu(fileName = "New Observable Float", menuName = "Observables/Float")]
public class ObservableFloat : ScriptableObject {
[System.Serializable]
public class Listener {
[DisplayAsString, HideInInspector] public int ID;
[DisplayAsString, HideLabel, HorizontalGroup] public string Observer;
[DisplayAsString, HideLabel, HorizontalGroup] public string Method;
[HideInInspector] public UnityAction<float> Callback;

public Listener(UnityAction<float> cb) {
ID = cb.GetHashCode();
Observer = cb.Target.ToString();
Method = cb.Method.ToString();
Callback = cb;
}
}
[Delayed]
[OnValueChanged("NotifyListeners")]
[SerializeField] private float m_Value;
public float Value {
get {
return m_Value;
}
set {
m_Value = value;
NotifyListeners();
}
}
[Tooltip("Log Invoke() calls")]
[SerializeField] bool Trace;
[Tooltip("Use try/catch around Invoke() calls so events continue to other listeners even if one fails")]
[SerializeField] bool CatchExceptions;
[ListDrawerSettings(DraggableItems = false, Expanded = true, ShowIndexLabels = false, ShowPaging = false, ShowItemCount = true)]
[SerializeField] List<Listener> listeners = new List<Listener>();

void Awake() {
// clear out whenever we start - just in case some observer doesn't properly remove himself
// maybe later I'll also add persistent listeners, but for now I don't see the use case
listeners = new List<Listener>();
}
void NotifyListeners() {
foreach (Listener listener in listeners) {
if (Trace) {
Debug.Log("invoking "+listener.Observer+" / "+listener.Method+ " / value = "+m_Value);
}
if (CatchExceptions) {
try {
listener.Callback.Invoke(m_Value);
} catch (System.Exception exception) {
Debug.LogException(exception, this);
}
} else {
listener.Callback.Invoke(m_Value);              
}
}
}
public void AddListener(UnityAction<float> func) { listeners.Add(new Listener(func)); }
public void RemoveListener(UnityAction<float> func) { listeners.RemoveAll(l => l.ID == func.GetHashCode()); }
}

这很有效，并为我提供了我想要的功能，不确定这是否是一个很好的解决方案，所以我将保留这个问题，以获得更好的答案。