是C＃的一次调度或多个调度语言？ [英] Is C# a single dispatch or multiple dispatch language?

问题描述

我想了解单个和多个调度是的，没错。

I'm trying to understand what single and multiple dispatch are, exactly.

我刚刚看了这样的：

<一href=\"http://en.wikipedia.org/wiki/Multiple_dispatch\">http://en.wikipedia.org/wiki/Multiple_dispatch

和来自定义在我看来，C＃和VB.Net是多重调度，即使选择超载，其中调用在编译时作出。

And from that definition is seems to me that C# and VB.Net are multiple-dispatch, even though the choice of which overload to call is made at compile-time.

我是正确这里，还是我失去了一些东西？
谢谢！

Am I correct here, or am I missing something? Thanks!

推荐答案

OK，我明白了微妙的区别在哪里函数重载是从多个分派不同的。

OK, I understood the subtle difference where function overloading is different from multiple-dispatch.

基本上，所不同的是选择在运行时或编译时是否要调用哪个方法。现在，我知道每个人的说这一点，但没有一个明显的例子，这听起来很明显的，因为C＃是静态类型和多语言派遣（显然对我来说，至少）似乎是动态类型。截至目前，只有这个定义多重调度和函数重载听起来完全一样给我。

Basically, the difference is whether which method to call is chosen at run-time or compile-time. Now, I know everybody's said this, but without a clear example this sounds VERY obvious, given that C# is statically typed and multiple-dispatch languages (apparently to me, at least) seem to be dynamically typed. Up to now, with just that definition multiple-dispatch and function overloading sounded exactly the same to me.

在哪里这使得真正的区别的情况是，当你有2个重载其中一个参数的类型不同的方法，但2类型是多态的，和你声明为较高类型的引用，具有来电下类型的对象...
（如果有人能想到更好的办法来恩preSS这个，请随时编辑此答案）

The case where this makes a real difference is when you have 2 overloads of a method which differ on the type of a parameter, but the 2 types are polymorphic, and you call with a reference declared as the higher type, which has an object of the lower type... (If someone can think of a better way to express this, please feel free to edit this answer)

例如：

int CaptureSpaceShip(IRebelAllianceShip ship) {}
int CaptureSpaceShip(XWing ship) {}

void Main() { 
  IRebelAllianceShip theShip = new XWing();
  CaptureSpaceShip(theShip);
}

X翼战机显然实现IRebelAllianceShip。
在这种情况下，第一方法将被调用，而如果C＃实现多调度，第二种方法将被称为

XWing obviously implements IRebelAllianceShip. In this case, the first method will be called, whereas if C# implemented multiple-dispatch, the second method would be called.

很抱歉的文档翻版......这在我看来，最清晰的方式来解释这种差异，而不仅仅是阅读定义为每个调度方法。

Sorry about the doc rehash... This seems to me the clearest way to explain this difference, rather than just reading the definitions for each dispatch method.

有关一个更正式的解释：
<一href=\"http://en.wikipedia.org/wiki/Double_dispatch#Double_dispatch_is_more_than_function_overloading\">http://en.wikipedia.org/wiki/Double_dispatch#Double_dispatch_is_more_than_function_overloading

For a more formal explanation: http://en.wikipedia.org/wiki/Double_dispatch#Double_dispatch_is_more_than_function_overloading

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