如何通过2种仿制药进入一个扩展方法 [英] How to pass 2 generics types into an extension method

问题描述

我创建了下面的扩展方法

I've created the following extension method

public static T Map<TEntity,T>(this TEntity entity) where TEntity : IEntity
{
    return Mapper.Map<TEntity, T>(entity);        
}

这允许以下

Db.ExchangeSets.FirstOrDefault().Map<ExchangeSet, ExchangeSetSimpleViewModel>()

不过，我想知道是否有反正我可以修改扩展方法，所以我可以调用一个缩如下：

However i'm wondering if there is anyway i can modify the extension method so i can call a shorted version as follows

Db.ExchangeSets.FirstOrDefault().Map<ExchangeSetSimpleViewModel>()

请注意：

不管是不是automapper应该使用这样是不是在问题的范围，其更多的事实调查团

Whether or not automapper should be used like this is not in the scope of the question, its more a fact finding mission

---

的更新

对于那些你在家里玩与斯科特的帮助评论我设法找到的对于automapper

For those of you playing at home, with the help of scotts comment i managed to find an additional solve for the above function at Generic extension method for automapper

public static T Map<T>(this IEntity entity) 
{
    return (T)Mapper.Map(entity, entity.GetType(), typeof(T));  
}

不过AutoMapper不谈，这是没有答案的实际问题，将标志择优因此

However AutoMapper aside, this is not the answer to the actual question and will mark on merit accordingly

推荐答案

在如果你想知道的为什么的这仅仅是不可能的，我会认为问题在于歧义：

In case you are wondering why this is just not possible, I'd think the problem lies with ambiguity:

public static T Map<TEntity,T>(this TEntity entity) where TEntity : IEntity
{
    return Mapper.Map<TEntity, T>(entity);        
}

public static T Map<T>(this ExchangeSet set)
{
    // ...
}

那么，哪种方法被调用？请记住，这仅仅是一个简单的例子。这是非常可能，有可能是未来局部类型推断的实现，但我想这将是太混乱，当谈到超载分辨率和成本/收益会完全失控。话又说回来，这只是猜测。

So, which method gets called? Keep in mind this is just a simple example. It's very well possible that there could be a future implementation of partial type inference, but I'd imagine it would be too confusing when it comes to overload resolution and the cost/benefit would be completely out of control. Then again, that's just speculation.

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