为什么不能将运算符作为参数传递? [英] Why is it not possible to pass an operator as an argument?

问题描述

我试图编写一个具有LINQ查询的方法.

I was trying to write a method which has a LINQ query.

这种方法:

DoSomething(Operator operator, string name)
{
  // if operator is ==
  // use == as comparison
  // if operator is !=
  // use != as comparison

  // pseudo query
  var result = from rec in collection
               where rec.name operator name
               select rec;
 }

我知道可以使用委托和Func and Action来完成此操作，并且对此进行了非常优雅的解释

I know this can be done using delegates and Func and Action and it was explained very elegantly here.

但是我想知道的是为什么一个方法只接受一个类型?为什么CLR不允许将运算符作为参数传递给方法?设计背后的想法是什么?

But what I wanted to know is why a method takes only a type? Why doesn't the CLR allow an operator to be passed as an argument to a method? What's the idea behind the design?

推荐答案

我要说的很简单，因为那不是操作符的处理方式.考虑一个这样的类:

I would say quite simply because that's just not how operators are handled. Consider a class like this:

public class A
{
    public int Prop { get; set; }
}

，现在考虑以下代码:

var a1 = new A() { Prop = 1 };
var a2 = new A() { Prop = 2 };

此刻我需要这样做:

if (a1.Prop == a2.Prop)

这将起作用，但是如果我能做到这一点呢?

and that would work, but what if I could just do this:

if (a1 == a2)

的确意味着上述内容.这就是操作员的工作.这就是为什么您不能将它们作为参数传递的原因.实际上，我刚刚展示的代码比您提供的代码更简洁.为什么不这样重载运算符:

and that really meant the aforementioned. That's what operators do. That's why you can't pass them as parameters. In fact, the code I just showed is more concise than what you're offering. Why not just overload the operators like this:

public static bool operator ==(A a1, A a2)
{
    return a1.Prop == a2.Prop;
}

，或者在您的情况下，在重载中运行适当的查询.就这么简单！

or in your case, run the appropriate query in the overload. Simple as that!

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