重载运算符==对的equals（） [英] Overloading operator== versus Equals()

问题描述

我在C＃项目合作上，到现在为止，我已经使用不可变对象和工厂，以确保类型的对象富可总是被比较与平等== 。

I'm working on a C# project on which, until now, I've used immutable objects and factories to ensure that objects of type Foo can always be compared for equality with ==.

富对象不能改变一旦创建，工厂始终返回一组给定的参数相同的对象。这个伟大的工程，并在整个code碱基我们假设 == 总是适用于检查平等的。

Foo objects can't be changed once created, and the factory always returns the same object for a given set of arguments. This works great, and throughout the code base we assume that == always works for checking equality.

现在我需要增加一些功能，引入了一个边缘的情况下，此将不总是有效。做最简单的事情是重载运算符== 为该类型，所以没有其他的code的项目需要改变。但是，这让我觉得作为一个code气味：超载运算符== ，而不是等于只是似乎不可思议，和我习惯了 == 检查引用相等，且约定等于检查对象相等（或任何术语是）。

Now I need to add some functionality that introduces an edge case for which this won't always work. The easiest thing to do is to overload operator == for that type, so that none of the other code in the project needs to change. But this strikes me as a code smell: overloading operator == and not Equals just seems weird, and I'm used to the convention that == checks reference equality, and Equals checks object equality (or whatever the term is).

这是一个合理的担忧，或者我应该继续前进，过载运算符== ？

Is this a legitimate concern, or should I just go ahead and overload operator ==?

推荐答案

我认为标准是，对于大多数类型，.Equals检查对象的相似性，和运营商 == 检查引用相等。

I believe the standard is that for most types, .Equals checks object similarity, and operator == checks reference equality.

我认为最好的做法是，对不可变类型，运营商 == 应检查相似性，以及 .Equals 。如果你想知道，如果他们真的是同一个对象，使用 .ReferenceEquals 。看到C＃字符串类的这样的一个例子。

I believe best practice is that for immutable types, operator == should be checking for similarity, as well as .Equals. And if you want to know if they really are the same object, use .ReferenceEquals. See the C# String class for an example of this.

这篇关于重载运算符==对的equals（）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！