c# 泛型，类型略有不同？

Question

注意两个扩展名，一个用于 float，一个用于 Vector3。

请注意，var( 调用中只有细微差别。

在 C# 中，这些可以写成一个泛型吗？

我的问题的实质是:

在泛型中，您能否根据类型的性质进行分支？

public static IEnumerator Tweeng( this float duration,
         System.Action<float> vary, float aa, float zz )
{
    float sT = Time.time;
    float eT = sT + duration;

    while (Time.time < eT)
    {   
        float t = (Time.time-sT)/duration;
        vary( Mathf.SmoothStep(aa,zz, t) ); // slight difference here
        yield return null;
    }

    vary(zz);
}

public static IEnumerator Tweeng( this float duration,
      System.Action<Vector3> vary, Vector3 aa, Vector3 zz )
{
    float sT = Time.time;
    float eT = sT + duration;

    while (Time.time < eT)
    {
        float t = (Time.time-sT)/duration;
        vary( Vector3.Lerp(aa,zz, t) ); // slight difference here
        yield return null;
    }

    vary(zz);
}

(对于任何 c# 专家阅读，代码示例在 Unity 中，您可以在协程中访问框架系统。)

对于任何 Unity 开发人员阅读，您如何调用 Tweeng 的示例

// tweeng z to 20 degrees in .12 seconds
StartCoroutine(.12f.Tweeng( (t)=>transform.Eulers(0f,0f,t), 0f,20f) );
// fade in alpha in .75 seconds
StartCoroutine(.75f.Tweeng( (u)=>{c.a=u;s.color=c;}, 0f,1f) );

(如果您是 Unity 的新手并且不熟悉扩展的基本概念，这里有一个 intro。)

Answer 1

如果你多做一个就可以了 Func<T,T>在调用 var 之前执行转换操作(您应该重命名，因为 var 是 C# 关键字)。

这是您可以采用的一种方法:

public static IEnumerator Tweeng<T>(
    this float duration
,   System.Action<T> varAction
,   T aa
,   T zz
) {
    Func<T,T,float,T> transform = MakeTransform<T>();
    float sT = Time.time;
    float eT = sT + duration;
    while (Time.time < eT) {   
        float t = (Time.time-sT)/duration;
        varAction(transform(aa, zz, t));
        yield return null;
    }
    varAction(zz);
}

private static Func<T,T,float,T> MakeTransform<T>() {
    if (typeof(T) == typeof(float)) {
        Func<float, float, float, float> f = Mathf.SmoothStep;
        return (Func<T,T,float,T>)(Delegate)f;
    }
    if (typeof(T) == typeof(Vector3)) {
        Func<Vector3, Vector3, float, Vector3> f = Vector3.Lerp;
        return (Func<T,T,float,T>)(Delegate)f;
    }
    throw new ArgumentException("Unexpected type "+typeof(T));
}

它甚至可以在线完成:

public static IEnumerator DasTweeng<T>( this float duration, System.Action<T> vary, T aa, T zz )
    {
    float sT = Time.time;
    float eT = sT + duration;

    Func<T,T,float,T> step;

    if (typeof(T) == typeof(float))
        step = (Func<T,T,float,T>)(Delegate)(Func<float, float, float, float>)Mathf.SmoothStep;
    else if (typeof(T) == typeof(Vector3))
        step = (Func<T,T,float,T>)(Delegate)(Func<Vector3, Vector3, float, Vector3>)Vector3.Lerp;
    else
        throw new ArgumentException("Unexpected type "+typeof(T));

    while (Time.time < eT)
        {
        float t = (Time.time-sT)/duration;
        vary( step(aa,zz, t) );
        yield return null;
        }
    vary(zz);
    }

也许更自然的成语是

    Delegate d;

    if (typeof(T) == typeof(float))
        d = (Func<float, float, float, float>)Mathf.SmoothStep;
    else if (typeof(T) == typeof(Vector3))
        d = (Func<Vector3, Vector3, float, Vector3>)Vector3.Lerp;
    else
        throw new ArgumentException("Unexpected type "+typeof(T));

    Func<T,T,float,T> step = (Func<T,T,float,T>)d;