C＃泛型+多态性解决方法？

Question

因此，我目前有一些包装Unity WWW类的方法。 HandleTexture，HandleText，HandleBytes ...，但这是很多复制粘贴的浪费。 我试图将其全部包装在一个通用的HandleResult方法下，该方法将事情交给幕后的_HandleResult。 在这一点上，C＃编译器抱怨无法将T静态地键入到Texture（带有closure(...);每一行closure(...);

private IEnumerator _HandleResult<T> (System.Action<T> closure, System.Action<string> onError){
    yield return webRequest;

    // Can't do a switch statement on Type, needs to be if/else chain :(
    if (SuccessWithoutErrors(onError)) {
        if(typeof(T) == typeof(Texture))
            closure(webRequest.texture);
        else if(typeof(T) == typeof(string))
            closure(webRequest.text);
        else if(typeof(T) == typeof(MovieTexture))
            closure(webRequest.movie);
        else if(typeof(T) == typeof(byte[]))
            closure(webRequest.bytes);
        else
            throw new System.NotSupportedException("Could not interpret response data as " + typeof(T).Name + ". Supported types include Texture, MovieTexture, byte[] and string.");
    }
}

我已经在这一点上停留了一段时间。 我对C＃相当陌生，所以也许我想要的根本不可行。 非常感谢来自对类型系统有更多了解的人的输入，或者为减少重复代码，我应该寻求哪些替代品以实现相同的效果。

Answer 1

如果直接转换为泛型类型，C＃似乎不喜欢它。 但是您可以先转换为object ，然后转换为通用类型：

private IEnumerator _HandleResult<T> (System.Action<T> closure, System.Action<string> onError){
    yield return webRequest;

    if (SuccessWithoutErrors(onError)) {
        if(typeof(T) == typeof(Texture))
            closure((T)(object)webRequest.texture);
        else if(typeof(T) == typeof(string))
            closure((T)(object)webRequest.text);
        else if(typeof(T) == typeof(MovieTexture))
            closure((T)(object)webRequest.movie);
        else if(typeof(T) == typeof(byte[]))
            closure((T)(object)webRequest.bytes);
        else
            throw new System.NotSupportedException("Could not interpret response data as " + typeof(T).Name + ". Supported types include Texture, MovieTexture, byte[] and string.");
    }
}

---

较干净的选项可能是提供执行属性选择的功能：

private IEnumerator _HandleResult<T> (System.Action<T> closure, Func<WebRequest, T> selector, System.Action<string> onError){
    yield return webRequest;

    if (SuccessWithoutErrors(onError)) { 
        closure(selector(webRequest)); 
    }
}

然后，您可以拥有一个函数签名并调用以下站点：

void DoSomethingWithTexture(Texture t) {}

_HandleResult<Texture>(DoSomethingWithTexture, wr => wr.Texture, onError);

第二种方法更干净，更灵活（如果以后要向要处理的对象添加Texture2属性，该怎么办？）但是需要更改API，并且可能更难以在现有代码中实现。

Answer 2

尝试这个：

    private IEnumerator _HandleResult<T>(object closure, System.Action<string> onError)
    {
        yield return webRequest;

        // Can't do a switch statement on Type, needs to be if/else chain :(
        if (true)
        {
            if (typeof(T) == typeof(Texture))
                ((System.Action<Texture>)closure)(webRequest.texture);
            else if (typeof(T) == typeof(string))
                ((System.Action<string>)closure)(webRequest.text);
            else if (typeof(T) == typeof(MovieTexture))
                ((System.Action<MovieTexture>)closure)(webRequest.movie);
            else if (typeof(T) == typeof(byte[]))
                ((System.Action<byte[]>)closure)(webRequest.bytes);
            else
                throw new System.NotSupportedException("Could not interpret response data as " + typeof(T).Name + ". Supported types include Texture, MovieTexture, byte[] and string.");
        }
    }