与调用接口实例泛型方法 [英] Calling a generic method with interface instances

问题描述

作为后续问题来这个

public interface IFeature  {  }

public class FeatureA : IFeature { }

IFeature a = new FeatureA();
Activate(a);

private static void Activate<TFeature>(TFeature featureDefinition) where TFeature : IFeature
{

}

我已了解，一旦 FeatureA 被强制转换为的iFeature 泛型方法总是会得到的iFeature 类型的参数。

I undestand, that once the FeatureA is casted to IFeature the generic method will always get IFeature as type parameter.

我们有我们提供了一个服务列表功能（列表与LT; iFeature的> ）。如果我们要遍历这些功能，通过每个泛型方法，我想有没有办法让在泛型方法比

We have a service with provides us with a list features (List<IFeature>). If we want to iterate over those features, passing each in the generic method, I guess there is no way to get the concrete type in the generic method other than

$ B等具体类型$ b
• 使用反射


• 使用动态变量来确定在运行时类型（的与调用正确的派生类型一个泛型方法）

• using reflection
• using a dynamic variable to determine the type on runtime (Calling a generic method with the correct derived type)

由于反射是非常昂贵的，我想用动态转换。是否有任何缺点调用的方法呀？不知怎的，我这样做的时候觉得脏： - ）

Since reflection is very costly, I would like to use the dynamic cast. Is there any downside to call the method that way? Somehow I feel dirty when doing that :-)

推荐答案

您可以使用访问者模式如下假设你可以修改你的代码库。否则，使用动态

You can use visitor pattern as follows assuming that you can modify your codebase. Otherwise, use dynamic.

public interface IFeature
{
    void Accept(Visitior visitor);
}

public class FeatureA : IFeature
{
    public void Accept(Visitior visitor)
    {
        visitor.Visit(this);
    }
}

public class FeatureB : IFeature
{
    public void Accept(Visitior visitor)
    {
        visitor.Visit(this);
    }
}

public class Visitior
{
    public void Visit<TFeature>(TFeature feature) where TFeature : IFeature
    {
        Console.WriteLine(typeof(TFeature) == feature.GetType());//True
    }
}

static void Main(string[] args)
{
    List<IFeature> features = new List<IFeature>
    {
         new FeatureA(),
         new FeatureB()
    };

    Visitior visitor = new Visitior();
    foreach (var item in features)
    {
        item.Accept(visitor);
    }
}

这篇关于与调用接口实例泛型方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！