传递一个接口集合 [英] Passing an Interface collection

问题描述

假设你有下面的类：

 类车：IPainting 
 {
 ... 
} 
  

那么这样的功能：

 无效AddCars（IEnumerable的<汽车>收集）
  

然后，代码片段是这样的：

 汽车宝马=新车（）; 
乘坐的奔驰车=新车（）; 
 
 IPainting一个=（IPainting）宝马; 
 IPainting B =（IPainting）奔驰; 
 
 IPainting [] =绘画新IPainting [] {A，B}; 
 
 AddCars（画）; //编译失败
  

这当然不能编译，因为AddCars（）方法只接受汽车集合，但它是个什么'画'阵列是由

我知道C＃4.0可能会提供一个解决方案。有任何解决方法今天呢？

谢谢，

阿尔贝托

< DIV CLASS =h2_lin>解决方案

C＃4不会让你写的代码，因为该方法 AddCars 预计的的IEnumerable<汽车> 它实现了 IPainting 。这并不意味着你可以通过的任何的类实现 IPainting （你可以比如有一个类自行车：IPainting 是无关的车类任何然而，它将使其他方式;如果你有无效AddCars（IEnumerable的< IPainting>集合）你可以传递一个列表<租车方式> 的方法

在那之前，你需要坚持通过车序列的方法，通过使用一些铸造的机制（如绘画。铸造<租车方式>（）其他答案建议）

Suppose you have the following class:

class Car : IPainting
{
 ...
}

Then a function like this:

void AddCars(IEnumerable<Car> collection)

Then a code snippet like this:

Car bmw = new Car();
Car mercedes = new Car();

IPainting a = (IPainting) bmw;
IPainting b = (IPainting) mercedes;

IPainting[] paintings = new IPainting[] {a, b};

AddCars(paintings); // fails to compile

This of course doesn't compile because the AddCars() method accepts only a collection of Cars but it is what the 'paintings' array is made of.

I know that C# 4.0 will probably provide a solution for this. Is there any workaround today for it?

Thanks,

Alberto

解决方案

C# 4 will not allow the code that you wrote, since the method AddCars expects an IEnumerable<Car> which implements IPainting. This does not mean that you can pass any class implementing IPainting (you could for instance have a class Bike : IPainting that has nothing to do with the Car class whatsoever. However, it will allow the other way around; if you have void AddCars(IEnumerable<IPainting> collection) you can pass a List<Car> to the method.

Until then, you will need to stick to passing Car sequences to the method, by using some casting mechanism (such as painting.Cast<Car>() suggested in other answers).

这篇关于传递一个接口集合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！