自定义类型，派生自 String [英] Custom Type, derived from String

问题描述

我正在处理一个 API，它以以下格式响应我的 POST 请求:

I am dealing with an API which responds to my POST requests under the following format:

Base64String:AnotherBase64String:Another:Etc

Base64String:AnotherBase64String:Another:Etc

因此，我有一些 Functions 和 Extensions 接受/返回以下格式的字符串:

I have therefore some Functions and Extensions which take/return strings under the following format:

• Base64 字符串
• Base64DoubleDotsBase64 字符串(见上文)

事情变得相当混乱，从某种意义上说，当一个函数接受一个 String 作为输入时，需要一些时间(阅读函数文档)来检查 String 应该是一个字符串，或者一个 Base64 字符串等.Strings Extensions 的智能感知也被入侵了.

Things are getting quite messy, in the sense that when a function takes a String as an input, it takes some time (reading the Function doc) to check if the String should be a string, or a Base64 string, etc. The intellisense for Strings Extensions is also getting invaded.

我正在考虑派生两个新的 Types 以便事情更容易.

I am considering deriving two new Types so that things are easier.

String 是 NotInheritable，所以我倾向于使用以下内容:

String is NotInheritable, so I am enclined to use the following:

Class Base64String
    Dim str As String
End Class

可以吗?看起来很简单(也很漂亮)，我很紧张.

Is that OK? It seems so simple (and beautiful), I am nervous.

PS:我的 Base64 字符串不需要任何操作，例如连接.唯一需要的扩展将是定制的.但是，如果有办法让字符串的本机扩展工作，我很想知道(出于好奇).

PS: my Base64 Strings will not require any operations such as concatenation. The only extensions required will be custom made. However, if there is a way to get the native extensions for string to work, I would be interested to know (out of curiosity).

推荐答案

Mark Hall 的帖子在 他的帖子中提到了 Widening，这正是我需要的:

Mark Hall's post mentions Widening in his post, which is just what I needed:

Public Class Base64String

    Private _String As String

    Private Sub New(ByVal value As String)
        Me._string = value
    End Sub

    Public Shared Widening Operator CType(ByVal value As String) As Base64String
        Return New Base64String(value)
    End Operator

    Public Overrides Function ToString() As String
        Return _String
    End Function

    Public Shared Operator &(ByVal s1 As Base64String, s2 As Base64String) As Base64String
        Dim temp As String = s1._String & s2._String
        Return New Base64String(temp)
    End Operator

End Class

像这样使用:

Dim MyString As Base64String = "abcd"
Console.WriteLine(MyString)

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