C＃泛型与类型的细微差别？ [英] c# generic with slight difference for types?

问题描述

注意两个扩展，一个用于浮动，一为的Vector3。

Notice the two extensions, one for float, one for Vector3.

注意有只在 VAR略有差别（电话。

在C＃中可以将这些写成一个作为通用??

In c# could these be written as one as a generic??

我的问题的实质是：

<中的通用EM>，可你的类型的性质分支

within a generic, can you branch on the nature of the type?

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);
}

的（BTW任何C＃大师阅读，代码例子是团结，在那里你一个协程访问框架系统。）的

有关的任​​何统一的开发者阅读，您怎么称呼Tweeng

For any Unity devs reading, examples of how you call Tweeng

// 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) );

（如果你是新来团结和不熟悉的扩展的基本概念，这里是一个< A HREF =htt​​p://stackoverflow.com/a/35629303/294884>介绍。）

(If you're new to Unity and not familiar with the basic concept of extensions, here's an intro.)

推荐答案

你可以做，如果你做一个额外的 Func键< T，T> 在调用 VAR之前要进行改造行动（你应该重新命名，因为 VAR 是一个C＃关键字）。

You can do it if you make an extra Func<T,T> that performs transformation before calling the var action (which you should rename, because var is a C# keyword).

下面是一个方法，你可以采取

Here is one approach that you could take:

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：

It can even be done inline:

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);
    }

也许一个更自然的习惯用法

Perhaps a more natural idiom is

    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;

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