Select Variable by its Name and Set - vb.net

Question

Module MyModule
Public Property alpha As String
Public Property beta As String
Public Property charlie As String
End MyModule
Public Class MyClass
Sub New()
Dim variableName as String = "beta"
MyModule.GetField(variableName) = "new value"
End Sub
End Class
I'm looking for a way to set the value of a variable in the module. But only the variable with the given variable name. The example above obviously does not work, but it provides an idea of my goal.
Imports System.Reflection
Public Class Form1
Sub New()
SetVariableByVariableName("beta", "new value")
End Sub
Public Sub SetVariableByVariableName(ByVal variableName As String, ByVal value As String)
Dim myFieldInfo As FieldInfo = GetType(MyModule).GetField(variableName, BindingFlags.Public Or BindingFlags.Static)
If myFieldInfo IsNot Nothing Then
myFieldInfo.SetValue(Nothing, value)
Console.WriteLine($"The value of {variableName} is now: {GetType(MyModule).GetField(variableName).GetValue(Nothing)}")
Else
Console.WriteLine($"Error: {variableName} does not exist in MyModule.")
End If
End Sub
End Class
Module MyModule
Public Property alpha As String
Public Property beta As String
Public Property charlie As String
End Module

Answer 1

You are on the right track with using reflection and FieldInfo to access the field in the MyModule module by its name. To set the value of the field, you need to pass two parameters to the SetValue method: the instance of the object (in this case, Nothing since the field is static), and the new value to assign to the field.
Here's how you can modify your SetVariableByVariableName method to achieve your goal:
Public Sub SetVariableByVariableName(ByVal variableName As String, ByVal value As String)
Dim myFieldInfo As FieldInfo = GetType(MyModule).GetField(variableName, BindingFlags.Public Or BindingFlags.Static)
If myFieldInfo IsNot Nothing Then
myFieldInfo.SetValue(Nothing, value)
Console.WriteLine($"The value of {variableName} is now: {MyModule.GetType().GetField(variableName).GetValue(Nothing)}")
Else
Console.WriteLine($"Error: {variableName} does not exist in MyModule.")
End If
End Sub
This method takes two parameters: the name of the variable you want to modify, and the new value you want to assign to it. It first retrieves the FieldInfo object for the variable with the given name from the MyModule module, using the GetField method of the Type class. Note that we have to specify the BindingFlags.Public and BindingFlags.Static flags to indicate that we want to access a public static field.
Next, it checks if the field exists. If it does, it calls the SetValue method on the FieldInfo object to assign the new value to the field. Finally, it retrieves the value of the field again to confirm that the new value has been assigned correctly, and prints it to the console.
If the field does not exist, it prints an error message to the console.
You can call this method from your MyClass constructor like this:
Public Class MyClass
Sub New()
SetVariableByVariableName("beta", "new value")
End Sub
End Class
This should set the value of the beta variable in the MyModule module to "new value" when a new instance of MyClass is created.

Answer 2

Here's an example based on my previous answer here:
MyModule:
Module MyModule
Public Property alpha As String
Public Property beta As String = "default beta"
Public Property charlie As String
End Module
Module1, which accesses the above "by name":
Imports System.Reflection
Module Module1
Sub Main()
Console.WriteLine("Module Property accessed directly: " & MyModule.beta)
Console.WriteLine("Module Property accessed 'by name': " & GetModulePropertyByName("MyModule", "beta"))
Console.WriteLine("Changing value...")
SetModulePropertyByName("MyModule", "beta", "Can you hear me now?")
Console.WriteLine("Module Property accessed directly: " & MyModule.beta)
Console.WriteLine("Module Property accessed 'by name': " & GetModulePropertyByName("MyModule", "beta"))
Console.WriteLine()
Console.Write("Press any key to quit...")
Console.ReadKey()
End Sub
Public Sub SetModulePropertyByName(ByVal moduleName As String, ByVal moduleField As String, ByVal value As String)
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 pi As PropertyInfo = myType.GetProperty(moduleField, flags)
If Not IsNothing(pi) Then
pi.SetValue(Nothing, value)
End If
End If
End Sub
Public Function GetModulePropertyByName(ByVal moduleName As String, ByVal moduleField As String) As Object
Dim O As Object = Nothing
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 pi As PropertyInfo = myType.GetProperty(moduleField, flags)
If Not IsNothing(pi) Then
O = pi.GetValue(Nothing)
End If
End If
Return O
End Function
End Module
Output:
Module Property accessed directly: default beta
Module Property accessed 'by name': default beta
Changing value...
Module Property accessed directly: Can you hear me now?
Module Property accessed 'by name': Can you hear me now?
Press any key to quit...