Display variable content dynamically - vb.net

Question

I'm trying to do this:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim my_variable as String = "hello"
Dim blabla as string = "my_variable"
msgbox(blabla) ' I want this to display: "hello"
End Sub
Any way you guys can help me in VB.NET (not C# please).

Answer 1

What you want cannot be done for a LOCAL variable like my_variable.
If that variable is at CLASS level, though, it can be done with REFLECTION.
If the variable is at class level and is PUBLIC, you can cheat and use CallByName:
Public Class Form1
Public counter As Integer = 911
Public my_variable As String = "Hello World!"
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim variable As String = TextBox1.Text
Try
Dim value As String = CallByName(Me, variable, CallType.Get)
MessageBox.Show(variable & " = " & value)
Catch ex As Exception
MessageBox.Show("Variable not found: " & variable)
End Try
End Sub
End Class
Type the name of the variable in TextBox1 and its value will be displayed in the message box....easy peasy.
If you don't want the variables to be public, then it can be accomplished via Reflection, but it doesn't look quite as simple and pretty. Look it up if you want to go that route.
--- EDIT ---
Here's a version that can find public members of a module:
Code:
Imports System.Reflection
Public Class Form2
Public counter As Integer = 911
Public my_variable As String = "Hello World!"
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
lblResults.Text = ""
Dim variable As String = TextBox1.Text
Try
Dim value As String = CallByName(Me, variable, CallType.Get)
lblResults.Text = variable & " = " & value
Catch ex As Exception
End Try
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
lblResults.Text = ""
Dim moduleName As String = txtModule.Text
Dim moduleField As String = txtModuleMember.Text
Dim myType As Type = Nothing
Dim myModule As [Module] = Nothing
For Each x In Assembly.GetExecutingAssembly().GetModules
For Each y In x.GetTypes
If y.Name.ToUpper = moduleName.ToUpper Then
myType = y
Exit For
End If
Next
If Not IsNothing(myType) Then
Exit For
End If
Next
If Not IsNothing(myType) Then
Dim flags As BindingFlags = BindingFlags.IgnoreCase Or BindingFlags.NonPublic Or BindingFlags.Public Or BindingFlags.Static Or BindingFlags.Instance
Dim fi As FieldInfo = myType.GetField(moduleField, flags)
If Not IsNothing(fi) Then
Dim value As String = fi.GetValue(Nothing)
lblResults.Text = moduleField & " = " & value
End If
End If
End Sub
End Class
Public Module PutThings
Public SomeValue As String = "...success!..."
End Module

Answer 2

My suggestion (just 1 idea, thinking out loud) would be to create a separate, global list of all of your variables, and every single time one of the variables you want to know the contents of changes, update the global list.
For example:
' Global declaration
Dim dictionary As New Dictionary(Of String, String)
Sub Form_Load()
' Add keys to all vars you want to lookup later
With dictionary
.Add("varCarrot", String.Empty)
.Add("varPerl", String.Empty)
End With
End Sub
Sub SomeSub()
strCarrot = "hello"
intPerl = 12
' Any time the vars change that you want to track, update the respective dictionary key
dictionary(varCarrot) = strCarrot
dictionary(varPerl) = intPerl.ToString
Do Until intPerl = 100
intPerl += 1
strCarrot = "hello " & intPerl
dictionary(varCarrot) = strCarrot
dictionary(varPerl) = intPerl.ToString
Loop
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
dim strLookup as String = text1.text ' the variable you want to lookup entered in the text1 textbox; i.e. "varCarrot"
' See if the requested key exists
If dictionary.ContainsKey(strLookup) Then messagebox.show(dictionary.Item(strLookup))
End Sub
When you're ready to no longer have that functionality in your app, such as when all done debugging it, and ready to finally release it, comment out all the dictionary stuff.