在本文中，我将带您了解与Unity相关的事件系统。我们将研究流行的方法，并详细分析接口的实现，这是我在Owlcat Games工作时遇到的。

内容

1. 什么是事件系统？
2. 现有的实现
   
   2.1。密钥订阅
   
   2.2。按事件类型
   
   2.3进行订阅。按订户类型订阅
3. 
   
   3.1.
   
   3.2.
   
   3.3.
4. 
   
   4.1.
   
   4.2.
   
   4.3.

1. ?

: UI, , , . :

1. . .
2. . .
3. . .

, . . , . , .

public class InputManager : MonoBehavioiur
{
    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.S))
        {
            EventSystem.RaiseEvent("quick-save");
        }
    }
}

public class SaveLoadManager : Monobehaviour
{
    private void OnEnable()
    {
        EventSystem.Subscribe("quick-save", QuickSave);
    }

    private void OnDisable()
    {
        EventSystem.Unsubscribe("quick-save", QuickSave);
    }

    private void QuickSave()
    {
        //  
        ...
    }
}

SaveLoadManager.OnEnable() QuickSave "quick-save". , EventSystem.RaiseEvent("quick-save") SaveLoadManager.QuickSave() . , null reference exception .

. , .

— , . . — .

2.

:

// 
EventSystem.Subscribe(_, _);

// 
EventSystem.RaiseEvent(_, );

, .

2.1.

_ Enum. — IDE, . . params object[] args. IDE .

// 
EventSystem.Subscribe("get-damage", OnPlayerGotDamage);

// 
EventSystem.RaiseEvent("get-damage", player, 10);

//  
void OnPlayerGotDamage(params object[] args)
{
    Player player = args[0] as Player;
    int damage = args[1] as int;
    ...
}

2.2.

, .

// 
EventSystem.Subscribe<GetDamageEvent>(OnPlayerGotDamage);

// 
EventSystem.RaiseEvent<GetDamageEvent>(new GetDamageEvent(player, 10));

//  
void OnPlayerGotDamage(GetDamageEvent evt)
{
    Player player = evt.Player;
    int damage = evt.Damage;
    Debug.Log($"{Player} got damage {damage}");
}

2.3.

. , . , .

public class UILog : MonoBehaviour, IPlayerDamageHandler
{
    void Start()
    {
        // 
        EventSystem.Subscribe(this);
    }

    //  
    public void HandlePlayerDamage(Player player, int damage)
    {
        Debug.Log($"{Player} got damage {damage}");
    }
}

// 
EventSystem.RaiseEvent<IPlayerDamageHandler>(h =>
    h.HandlePlayerDamage(player, damage));

3.

. , . " ".

3.1.

, , .

. , :

public interface IQiuckSaveHandler : IGlobalSubscriber
{
    void HandleQuickSave();
}

, , IGlobalSubscriber. - , . IGlobalSubscriber , .

:

public class SaveLoadManager : Monobehaviour, IQiuckSaveHandler
{
    private void OnEnable()
    {
        EventBus.Subscribe(this);
    }

    private void OnDisable()
    {
        EventBus.Unsubscribe(this);
    }

    private void HandleQuickSave()
    {
        //  
        ...
    }
}

Subscribe.

public static class EventBus
{
    private static Dictionary<Type, List<IGlobalSubscriber>> s_Subscribers
        = new Dictionary<Type, List<IGlobalSubscriber>>();

    public static void Subscribe(IGlobalSubscriber subscriber)
    {
        List<Type> subscriberTypes = GetSubscriberTypes(subscriber.GetType());
        foreach (Type t in subscriberTypes)
        {
            if (!s_Subscribers.ContainsKey(t))
                s_Subscribers[t] = new List<IGlobalSubscriber>();
            s_Subscribers[t].Add(subcriber);
        }
    }
}

s_Subscribers. , .

GetSubscriberTypes . -, . : IQiuckSaveHandler — SaveLoadManager .

subscriberTypes. s_Subscribers .

GetSubscribersTypes:

public static List<Type> GetSubscribersTypes(IGlobalSubscriber globalSubscriber)
{
    Type type = globalSubscriber.GetType();
    List<Type> subscriberTypes = type
        .GetInterfaces()
        .Where(it =>
                it.Implements<IGlobalSubscriber>() &&
                it != typeof(IGlobalSubscriber))
        .ToList();
    return subscriberTypes;
}

, , IGlobalSubscriber. , .

, EventBus , .

3.2.

, . InputManager 'S', .

:

public class InputManager : MonoBehavioiur
{
    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.S))
        {
            EventBus.RaiseEvent<IQiuckSaveHandler>(
                IQiuckSaveHandler handler => handler.HandleQuickSave());
        }
    }
}

RaiseEvent:

public static class EventBus
{
    public static void RaiseEvent<TSubscriber>(Action<TSubscriber> action)
    where TSubscriber : IGlobalSubscriber
    {
        List<IGlobalSubscriber> subscribers = s_Subscribers[typeof(TSubscriber)];
        foreach (IGlobalSubscriber subscriber in subscribers)
        {
            action.Invoke(subscriber as TSubscriber);
        }
    }
}

TSubscriber IQiuckSaveHandler. IQiuckSaveHandler handler => handler.HandleQuickSave() action, IQiuckSaveHandler. action HandleQuickSave .

IQiuckSaveHandler handler => handler.HandleQuickSave() C# h => h.HandleQuickSave().

, .

3.3.

. :

public interface IQuickSaveLoadHandler : IGlobalSubscriber
{
    void HandleQuickSave();
    void HandleQuickLoad();
}

, , .

, - . 1 . .

public interface IUnitDeathHandler : IGlobalSubscriber
{
    void HandleUnitDeath(Unit deadUnit, Unit killer);
}

public class UILog : IUnitDeathHandler
{
    public void HandleUnitDeath(Unit deadUnit, Unit killer)
    {
        Debug.Log(killer.name + " killed " + deadUnit.name);
    }
}

public class Unit 
{
    private int m_Health

    public void GetDamage(Unit damageDealer, int damage)
    {
        m_Health -= damage;
        if (m_Health <= 0)
        {
            EventBus.RaiseEvent<IQiuckSaveHandler>(h =>
                h.HandleUnitDeath(this, damageDealer));
        }
    }
}

.

4.

, , .

4.1.

. , try catch:

public static void RaiseEvent<TSubscriber>(Action<TSubscriber> action)
where TSubscriber : IGlobalSubscriber
{
    List<IGlobalSubscriber> subscribers = s_Subscribers[typeof(TSubscriber)];
    foreach (IGlobalSubscriber subscriber in subscribers)
    {
        try
        {
            action.Invoke(subscriber as TSubscriber);
        }
        catch (Exception e)
        {
            Debug.LogError(e);
        }
    }
}

4.2.

GetSubscribersTypes , . , .

private static Dictionary<Type, List<Types>> s_CashedSubscriberTypes = 
    new Dictionary<Type, List<Types>>()

public static List<Type> GetSubscribersTypes(
    IGlobalSubscriber globalSubscriber)
{
    Type type = globalSubscriber.GetType();
    if (s_CashedSubscriberTypes.ContainsKey(type))
        return s_CashedSubscriberTypes[type];

    List<Type> subscriberTypes = type
        .GetInterfaces()
        .Where(it =>
                it.Implements<IGlobalSubsriber>() &&
                it != typeof(IGlobalSubsriber))
        .ToList();

    s_CashedSubscriberTypes[type] = subscriberTypes;
    return subscriberTypes;
}

4.3.

, - :

public static void Unsubscribe(IGlobalSubsriber subcriber)
{
    List<Types> subscriberTypes = GetSubscriberTypes(subscriber.GetType());
    foreach (Type t in subscriberTypes)
    {
        if (s_Subscribers.ContainsKey(t))
            s_Subscribers[t].Remove(subcriber);
    }
}

.

Collection was modified; enumeration operation might not execute.

, - foreach .

foreach (var a in collection)
{
    if (a.IsBad())
    {
        collection.Remove(a); //  
    }
}

, .

, . , , . , , null. .

public class SubscribersList<TSubscriber> where TSubscriber : class
{
    private bool m_NeedsCleanUp = false;

    public bool Executing;

    public readonly List<TSubscriber> List = new List<TSubscriber>();

    public void Add(TSubscriber subscriber)
    {
        List.Add(subscriber);
    }

    public void Remove(TSubscriber subscriber)
    {
        if (Executing)
        {
            var i = List.IndexOf(subscriber);
            if (i >= 0)
            {
                m_NeedsCleanUp = true;
                List[i] = null;
            }
        }
        else
        {
            List.Remove(subscriber);
        }
    }

    public void Cleanup()
    {
        if (!m_NeedsCleanUp)
        {
            return;
        }

        List.RemoveAll(s => s == null);
        m_NeedsCleanUp = false;
    }
}

EventBus:

public static class EventBus
{
    private static Dictionary<Type, SubscribersList<IGlobalSubcriber>> s_Subscribers
        = new Dictionary<Type, SubscribersList<IGlobalSubcriber>>();
}

RaiseEvent:

public static void RaiseEvent<TSubscriber>(Action<TSubscriber> action)
where TSubscriber : IGlobalSubscriber
{
    SubscribersList<IGlobalSubscriber> subscribers = s_Subscribers[typeof(TSubscriber)];

    subscribers.Executing = true;
    foreach (IGlobalSubscriber subscriber in subscribers.List)
    {
        try
        {
            action.Invoke(subscriber as TSubscriber);
        }
        catch (Exception e)
        {
            Debug.LogError(e);
        }
    }
    subscribers.Executing = false;
    subscribers.Cleanup();
}

, . , , . , . , .

5.

. . .

我们的解决方案的特点是使用接口。如果您仔细考虑一下，在事件系统中使用接口是很合逻辑的。毕竟，最初是发明接口来定义对象的功能的。在我们的案例中，我们正在谈论对游戏中某些事件做出反应的能力。

将来，可以针对特定项目开发该系统。例如，在我们的游戏中，有特定单元事件的订阅。另一个呼叫并完成了一些机械事件。

链接不是存储库。