Creating Extension Methods in VB
I received a question about how to create extension methods in VB. It turns out that the key difference is that the extension must be defined in a Module and not in a class.
Thus, building on the code from the previous example, we end up with the same Page.xaml and a very similar Page.xaml.vb and a quite different Extension.vb
Here is Extension.vb
Imports Microsoft.VisualBasic
Imports System
Namespace GetLastNFromString
Module ExtensionModule
<System.Runtime.CompilerServices.Extension()> _
Public Function Right(ByVal s As String, _
ByVal howMany As Integer) As String
If howMany <= s.Length Then
Return s.Substring(s.Length - howMany, howMany)
Else
Return s
End If
End Function
End Module
End Namespace
And here is Page.xaml.vb
Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Net
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Animation
Imports System.Windows.Shapes
Namespace GetLastNFromString
Partial Public Class Page
Inherits UserControl
Public Sub New()
InitializeComponent()
AddHandler GoButton.Click, AddressOf GoButton_Click
End Sub
Private Sub GoButton_Click( _
ByVal sender As Object, _
ByVal e As RoutedEventArgs)
ResultBox.Text = _
StringToParse.Text.Right(Convert.ToInt32 (NumberToGet.Text))
End Sub
End Class
End Namespace
For completeness, here is Page.xaml
<UserControl x:Class="GetLastNFromString.Page"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Width="650"
Height="200">
<Grid x:Name="LayoutRoot"
Background="Bisque">
<Grid.RowDefinitions>
<RowDefinition Height="1.5*" />
<RowDefinition Height="1*" />
<RowDefinition Height="1*" />
<RowDefinition Height="1*" />
<RowDefinition Height="1*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*" />
<ColumnDefinition Width="2*" />
</Grid.ColumnDefinitions>
<TextBlock HorizontalAlignment="Center"
Margin="0,0,0,0"
x:Name="Title"
Grid.ColumnSpan="2"
FontFamily="Georgia"
FontSize="36"
Foreground="#FF0C42EE"
Text="Last n Traditional (VB)"
TextWrapping="Wrap" />
<TextBlock x:Name="String_Prompt"
Text="String"
Width="Auto"
Grid.Row="1"
Margin="0,0,10,0"
Foreground="Blue"
FontFamily="Georgia"
FontSize="24"
VerticalAlignment="Bottom"
HorizontalAlignment="Right" />
<TextBlock x:Name="NumChars_Prompt"
Text="Number To Get"
Grid.Row="2"
Margin="0,0,10,0"
Foreground="Blue"
FontFamily="Georgia"
FontSize="24"
VerticalAlignment="Bottom"
HorizontalAlignment="Right" />
<TextBlock x:Name="Result"
Text="Result"
Grid.Row="3"
Margin="0,0,10,0"
Foreground="Blue"
FontFamily="Georgia"
FontSize="24"
VerticalAlignment="Bottom"
HorizontalAlignment="Right" />
<TextBox FontFamily="Georgia"
FontSize="24"
HorizontalAlignment="Left"
Margin="5,0,0,2"
x:Name="StringToParse"
VerticalAlignment="Bottom"
Width="400"
Grid.Column="1"
Grid.Row="1"
Text="" />
<TextBox x:Name="NumberToGet"
FontFamily="Georgia"
FontSize="24"
HorizontalAlignment="Left"
Margin="5,0,0,0"
VerticalAlignment="Bottom"
Width="Auto"
Grid.Column="1"
Grid.Row="2"
Text="?" />
<TextBlock x:Name="ResultBox"
HorizontalAlignment="Left"
Margin="5,0,0,0"
VerticalAlignment="Bottom"
Grid.Column="1"
Grid.Row="3"
FontFamily="Georgia"
FontSize="24"
Text="" />
<Button x:Name="GoButton"
Content=" Go! "
Grid.Row="4"
Grid.Column="0"
FontFamily="Georgia"
FontSize="18"
Foreground="Blue"
HorizontalAlignment="Right"
Margin="5"
Width="Auto" />
</Grid>
</UserControl>