如何隐藏通过扩展方法的成员方法 [英] How to Hide a member method by an Extension Method

问题描述

 公共静态MyClass类
{
    公共静态无效的添加＆LT; T＆GT;（名单＆LT; T＆GT;清单，T项）
    {
        list.Add（项目）;
        Console.WriteLine（item.ToString（））;
    }
}
 

然后

 名单，其中，串＆GT;名单=新的名单，其中，串＆GT;（）{1，2};
list.Add（3）;
 

但成员方法将被调用。

反正是有打电话给我扩展方法这样？

我不希望这样称呼它：

  MyClass.Add（列表项）
 

解决方案

您不能。实例方法的总是的采取precedence了扩展方法，假设他们是适用的。会员分辨率将只考虑一旦它没有找到一个非扩展法选项扩展方法。

我建议你只需重命名你的方法 - 除非一点是透明调用此方法与现有的code

如果你做它需要一个的IList＆LT; T＆GT; 而不是名单，其中，T＆GT; ，你可以创建一个它实现包装类型的IList＆LT; T＆GT; 和代表所有呼叫到包列表，执行任何额外的任务，当您去。然后，您可以的也的编写扩展方法的IList＆LT; T＆GT; 其创建的包装 - 这将允许在某些情况下，更流畅的语法。我个人preFER包装的方法来推导一个新的集合类型，因为它意味着你可以用它与您现有的集合，使得code的变化可能较小......但是这一切都取决于你想要什么做的。

public static class MyClass
{
    public static void Add<T>(this List<T> list, T item)
    {
        list.Add(item);
        Console.WriteLine(item.ToString());
    }
}

then

List<string> list = new List<string>(){"1","2"};
list.Add("3");

But the member method would be called.

Is there anyway to call my Extension Method this way?

I don't want to call it like this:

MyClass.Add(list, item)

解决方案

You can't. Instance methods always take precedence over extension methods, assuming they're applicable. Member resolution will only consider extension methods once it's failed to find a non-extension-method option.

I would suggest you simply rename your method - unless the point was to call this method transparently with existing code.

If you made it take an IList<T> instead of List<T>, you could create a wrapper type which implements IList<T> and delegates all calls onto the wrapped list, performing any extra tasks as you go. You could then also write an extension method to IList<T> which created the wrapper - which would allow for more fluent syntax in some cases. Personally I prefer the wrapper approach to deriving a new collection type, as it means you can use it with your existing collections, making the code changes potentially smaller... but it all depends on what you're trying to do.

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