如何为我的类提供自定义转换支持？ [英] How do I provide custom cast support for my class?

问题描述

如何提供支援将我的课程转换为其他类型？例如，如果我有自己的实现管理一个 byte [] ，我想让人们把我的类转换为 byte [] ，这将只是返回私有成员，我将如何做到这一点？

How do I provide support for casting my class to other types? For example, if I have my own implementation of managing a byte[], and I want to let people cast my class to a byte[], which will just return the private member, how would I do this?

这是常见的做法是让他们也把这个字符串，或者我应该覆盖 ToString（）（或两者）？

Is it common practice to let them also cast this to a string, or should I just override ToString() (or both)?

推荐答案

您需要使用 隐含 或 显式 ，具体取决于您是否希望用户投放它，还是希望自动发生。一般来说，一个方向总是工作的，那是你使用 implicit 的地方，而另一个方向有时可能会失败，这是你使用 explicit 。

You would need to override the conversion operator, using either implicit or explicit depending on whether you want users to have to cast it or whether you want it to happen automagically. Generally, one direction will always work, that's where you use implicit, and the other direction can sometimes fail, that's where you use explicit.

语法如下：

public static implicit operator dbInt64(Byte x)
{
    return new dbInt64(x);
}

或

public static explicit operator Int64(dbInt64 x)
{
    if (!x.defined)
        throw new DataValueNullException();
    return x.iVal;
}



< MyType - > byte [] 将始终工作）：

For your example, say from your custom Type (MyType --> byte[] will always work):

public static implicit operator byte[] (MyType x)
{
    byte[] ba = // put code here to convert x into a byte[]
    return ba;
}

或

public static explicit operator MyType(byte[] x)
{
    if (!CanConvert)
        throw new DataValueNullException();

    // Factory to convert byte[] x into MyType
    MyType mt = MyType.Factory(x);
    return mt;
}

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