隐式转换运算符和等于运算符 [英] Implicit cast operator and the equality operator

问题描述

说我有一个简单的对象，它支持隐式转换为System.String

Say I have a simple object which supports implicit casting to System.String

public sealed class CompanyCode
{
    public CompanyCode(String value)
    {
        // Regex validation on value format
        _value = value;
    }

    private readonly String _value;

    public override String ToString()
    {
        return _value;
    }

    static public implicit operator String(CompanyCode code)
    {
        if(code == null)
            return null;

        return code.ToString();
    }
}

现在让我在程序的其他部分我进行说

Now lets say in another part of my program I perform a comparison with a string:

var companyCode = { some company code object }

if (companyCode == "MSFTUKCAMBS")
    // do something...

什么是编译器与 == 运营商在做什么？是它隐含铸造企业编码为字符串，并运行 System.String == 的实施？难道使用 System.Object的== 的实施？或将编译器只是抱怨我？ （我没有一个编译器检查现在这个右）。

What is the compiler doing with the == operator? Is it implicitly casting companyCode to a string and running the System.String == implementation? Is it using the System.Object == implementation? Or will the compiler just complain at me? (I don't have a compiler to check this right now).

据我可以看到我有几个其他的选择。

As far as I can see I have a couple of other options.

• 实施的 = =（字符串x）运营商的企业编码。


• 实施 IEquatable<弦乐方式>对企业编码接口

• Implement an ==(String x) operator on CompanyCode.
• Implement the IEquatable<String> interface on CompanyCode.

是否有任何（或两者）这些选项最好？

Would any (or both) of these options be preferable?

推荐答案

我个人建议不要使用运算符重载中的这些情况下的。这是一种混淆找上了代码，了解正在发生的事情。

I personally would suggest do not use operator overloading, in these cases. It's kind of confusing looking on the code, to understand what is going on.

这是一个更好的，海事组织，有一些功能是esplicitly的清单的比较操作，或者像乔恩表明，使用属性。

It's a much better, imo, having some function that esplicitly manifests comparison operation, or, like Jon suggests, use a property.

在短期讲清楚你的代码，你会得到什么比较读卡器。

In short make it clear for the reader of your code what you're gonna to compare.

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