Unity/Csharp/Action

Actionとは

関数を変数にできるもの

Actionサンプル1

System.Action<string> OnMsg = delegate (string msg) { };
OnMsg += (msg) =>
{
    Debug.Log("msg1:" + msg);
};

// 呼び出し
OnMsg("hello");

ラムダ式だとこうかける

System.Action<string> OnMsg = (msg) =>
{
    Debug.Log("msg1:" + msg);
};

// 呼び出し
OnMsg("hello");

Actionサンプル2(別クラス呼び出し)

public class ActionScene : MonoBehaviour
{
    void Start()
    {
        var eventActionClass = new EventActionClass();
        eventActionClass.Setup(
             callback: () =>
             {
                 Debug.Log("callback");
             });
    }
}
public class EventActionClass
{
    public void Setup(System.Action callback)
    {
        callback(); // callback.Invoke(); でもOK
    }
}

Setup()の部分、ラムダ式の変数に分けると、こうかける

public class ActionScene : MonoBehaviour
{
    void Start()
    {
        System.Action callback = () =>
        {
            Debug.Log("callback");
        };
        var eventActionClass = new EventActionClass();
        eventActionClass.Setup(
             callback: callback);
    }
}

Actionサンプル3(Actionを複数呼び出し)

public class ActionScene : MonoBehaviour
{
    void Start()
    {
        var eventActionClass = new EventActionClass();
        eventActionClass.Setup(
             callOnAction: () =>
             {
                 Debug.Log("callOnAction");
             },
             callOffAction: () =>
             {
                 Debug.Log("callOffAction");
             });
    }
}
public class EventActionClass
{
    public void Setup(System.Action callOnAction, System.Action callOffAction)
    {
        callOnAction();
        callOffAction();
    }
}

Setup()の部分、ラムダ式の変数に分けると、こうかける

public class ActionScene : MonoBehaviour
{
    void Start()
    {
        System.Action onAction = () =>
        {
            Debug.Log("callOnAction");
        };
        System.Action offAction = () =>
        {
            Debug.Log("callOffAction");
        };
        var eventActionClass = new EventActionClass();
        eventActionClass.Setup(
             callOnAction: onAction,
             callOffAction: offAction);
    }
}

Actionサンプル4、引数で渡して戻す

public class ActionScene : MonoBehaviour
{
    void Start()
    {
        System.Action<string> event = (name) =>
        {
            Debug.Log(name); // hogeが返ってくる
        };
        var sampleLogic new SampleLogic();
        sampleLogic.Load(event);
    }
}
public class SampleLogic
{
    public void Load(System.Action<string> event)
    {
        event("hoge");
    }
}