为什么 C#(或 .NET)不允许我们在接口中放置静态/共享方法? [英] Why shouldn't C#(or .NET) allow us to put a static/shared method inside an interface?

问题描述

为什么 C#(或 .NET)不允许我们在接口中放置静态/共享方法?

Why shouldn't C#(or .NET) allow us to put a static/shared method inside an interface?

看似重复来自 这里.但我的想法有点不同，我只想为我的插件(接口)添加一个助手

seemingly duplicate from here. but my idea is a bit different one, I just want to put a helper for my plugins(interface)

C# 至少不应该允许这个想法吗?

shouldn't C# at least allow this idea?

namespace MycComponent
{

    public interface ITaskPlugin : ITaskInfo
    {
        string Description { get; }
        string MenuTree { get; }
        string MenuCaption { get; }

        void ShowTask(Form parentForm);
        void ShowTask(Form parentForm, Dictionary<string, object> pkColumns);

        ShowTaskNewDelegate ShowTaskNew { set; get; }
        ShowTaskOpenDelegate ShowTaskOpen { set; get; }        

        // would not compile with this:
        public static Dictionary<string, ITaskPlugin> GetPlugins(string directory)
        {

            var l = new Dictionary<string, ITaskPlugin>();

            foreach (string file in Directory.GetFiles(directory))
            {
                var fileInfo = new FileInfo(file);   
                if (fileInfo.Extension.Equals(".dll"))
                {
                    Assembly asm = Assembly.LoadFile(file);       
                    foreach (Type asmType in asm.GetTypes())
                    {

                        if (asmType.GetInterface("MycComponent.ITaskPlugin") != null)
                        {
                            var plugIn = (ITaskPlugin)Activator.CreateInstance(asmType);
                            l.Add(plugIn.TaskName, plugIn);
                        }

                    }


                }
            }

            return l;
        } // GetPlugins.  would not compile inside an interface
    }



    /* because of the error above, I am compelled to 
       put the helper method in a new class. a bit overkill when the method should
       be closely coupled to what it is implementing */
    public static class ITaskPluginHelper
    {
        public static Dictionary<string, ITaskPlugin> GetPlugins(string directory)
        {

            var l = new Dictionary<string, ITaskPlugin>();

            foreach (string file in Directory.GetFiles(directory))
            {
                var fileInfo = new FileInfo(file);   
                if (fileInfo.Extension.Equals(".dll"))
                {
                    Assembly asm = Assembly.LoadFile(file);       
                    foreach (Type asmType in asm.GetTypes())
                    {

                        if (asmType.GetInterface("MycComponent.ITaskPlugin") != null)
                        {
                            var plugIn = (ITaskPlugin)Activator.CreateInstance(asmType);
                            l.Add(plugIn.TaskName, plugIn);
                        }

                    }


                }
            }

            return l;
        } // GetPlugins    
    } // ITaskPluginHelper
}

推荐答案

接口的概念是代表一个契约，而不是实现.

The idea of an interface is to represent a contract, not implementation.

我不记得 IL 是否真的确实允许在接口中实现静态方法——我偷偷地怀疑它确实如此——但这有点混淆了这个概念.

I can't remember offhand whether IL actually does allow static methods with implementations in interfaces - I've a sneaky suspicion that it does - but that muddies the concept somewhat.

我明白你的意思 - 有时了解哪些与接口相关的辅助方法是有用的(并且扩展方法在那里特别相关)，但我个人还是想把它们放在一个单独的类中，只是为了保持思维模型清洁.

I can see your point - it's sometimes useful to know what helper methods are available which are connected with an interface (and extension methods are particularly relevant there) but I would personally want to put those in a separate class anyway, just to keep the mental model clean.

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