VB.Net 扩展函数不是字符串的成员

Question

我正试图将整个 asp.net 应用程序中的一些通用功能折叠到一些字符串扩展方法中，但我运行遇到了一个问题，即我们的网站正在排除编译器错误，这些方法是不是 String 的成员。

这是我创建的 Utilities 命名空间中的模块定义：

Imports System
Imports System.IO
Imports System.Runtime.CompilerServices
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports Telerik.Web.UI
Imports System.Data
Imports System.Collections.Generic
Imports System.Data.SqlClient

Namespace Utilities    
    'This extension extends the String class with new functions to check string validity.  Add any such new functions here
    <Extension()> _
    Public Module StringExtensions
        <Extension()> _
        Public Function IsAlphaNumeric(targ As String) As Boolean
            Return System.Text.RegularExpressions.Regex.IsMatch(targ, "^[a-zA-Z0-9]+$")
        End Function

        Public Function IsNumeric(targ As String) As Boolean
            Return System.Text.RegularExpressions.Regex.IsMatch(targ, "^[0-9]+$")
        End Function

        Public Function RegexRemove(targ As String, rpl As String) As String
            Return Regex.Replace(targ, rpl, "")
        End Function
    End Module
End Namespace

这是我尝试从中调用扩展方法的位置以及调用其中之一的示例：

Imports System
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Data
Imports System.Collections.Generic
Imports System.Web.UI.HtmlControls
Imports Telerik.Web.UI
Imports System.IO
Imports System.Data.SqlClient
Imports System.Runtime.CompilerServices
Imports Utilities
Imports Utilities.StringExtensions
Imports Utilities.PageOps
Imports Utilities.DBChecks

Public Class UserDashboard
    Inherits System.Web.UI.Page

    '...

    Private Function GetRoleLst(rMap As Collections.Generic.Dictionary(Of String, String)) As List(Of String)
        Dim rLst As New List(Of String)()

        For Each kvp As KeyValuePair(Of String, String) In rMap
            For Each con As Control In ThRolePanel.Controls
                If TypeOf con Is CheckBox Then
                    Dim conID As String = con.ID
                    If DirectCast(con, CheckBox).Checked And conID.RegexRemove("\s") = kvp.Key Then
                        rLst.Add(kvp.Value)
                    End If
                End If
            Next
        Next
    End Function
End Class

我们的 Web.config 文件指向 .net 4.0，并且 System.Core 已添加到程序集列表中。这是编译选项卡：

<compilation debug="true" strict="false" explicit="true" targetFramework="4.0">
      <assemblies>
         <add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="Microsoft.ReportViewer.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="Microsoft.Build.Framework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="System.Management, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="System.Security, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
        <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Data.Entity.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Speech, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Runtime.Serialization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="System.Data.DataSetExtensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
        <add assembly="Telerik.ReportViewer.WebForms, Version=8.2.14.1204, Culture=neutral, PublicKeyToken=a9d7983dfcc261be" />
        <add assembly="Telerik.Reporting.Service, Version=8.2.14.1204, Culture=neutral, PublicKeyToken=a9d7983dfcc261be" />
        <add assembly="Telerik.Reporting, Version=8.2.14.1204, Culture=neutral, PublicKeyToken=a9d7983dfcc261be" />
      </assemblies>

      <buildProviders>
        <add extension=".rdlc" type="Microsoft.Reporting.RdlBuildProvider, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
        <add extension=".edmx" type="System.Data.Entity.Design.AspNet.EntityDesignerBuildProvider" />
      </buildProviders>
    </compilation>

已经查看了一些 SO 问题、VB 扩展函数指南和 .net 文档，但 none 到目前为止帮助我解决了这个问题。

更新

所以出于直觉，我尝试通过这样的命名空间访问扩展方法：

Utilities.RegexReplace(con.ID,"\s")

并且有效，但是如果我尝试将其作为 String 的扩展来访问，我仍然遇到上一个问题，它报告 "RegexReplace" is not a member of string 错误。由于某种原因，扩展方法似乎并没有真正扩展 String。

Answer 1

您已将 Extension 属性添加到 IsAlphaNumeric，但未添加到 IsNumeric 或 RegexRemove。这个：

<Extension()> _
Public Function IsAlphaNumeric(targ As String) As Boolean
    Return System.Text.RegularExpressions.Regex.IsMatch(targ, "^[a-zA-Z0-9]+$")
End Function

Public Function IsNumeric(targ As String) As Boolean
    Return System.Text.RegularExpressions.Regex.IsMatch(targ, "^[0-9]+$")
End Function

Public Function RegexRemove(targ As String, rpl As String) As String
    Return Regex.Replace(targ, rpl, "")
End Function

应该是这样的：

<Extension()> _
Public Function IsAlphaNumeric(targ As String) As Boolean
    Return System.Text.RegularExpressions.Regex.IsMatch(targ, "^[a-zA-Z0-9]+$")
End Function

<Extension()> _
Public Function IsNumeric(targ As String) As Boolean
    Return System.Text.RegularExpressions.Regex.IsMatch(targ, "^[0-9]+$")
End Function

<Extension()> _
Public Function RegexRemove(targ As String, rpl As String) As String
    Return Regex.Replace(targ, rpl, "")
End Function

VB.Net 扩展函数不是字符串的成员

VB.Net Extension Function Not a Member of String

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