Passing parameter into function to create variable name - excel

Question

I want to use global variables in my workbook and in the ThisWorkbook code. I declared the following varaibles
Public position_1 as string
Public position_2 as string
If I want to see the value of those variables I believe they need to be fully qualified so
Debug.Print ThisWorkbook.position_1
Debug.Print ThisWorkbook.position_2
I have written a UDF which I will pass in an integer to represent which variable I am looking for. I will only be passing in a single number and not a full variable name. I am trying to find a way to use this integer to concatenate with "position_" to display the value of the global variable, ThisWorkbook.position_1, ThisWorkbook.position_2, etc.
Function Test_Global_Var(position as Integer)
Dim variable_name As String
variable_name = "position_" & position
Debug.Print ThisWorkbook.variable_name
End Function
So when I call
Test_Global_Var(1)
my immediate window should display the value of
ThisWorkbook.position_1

Answer 1

The code below produces the following debug output
2 values defined.
ThisWorkbook.Position(0)
First Value
ThisWorkbook.Position(1)
Second Value
It uses a private array in the workbook named m_position. The contents are accessed by a global property ThisWorkbook.Position(index).
In a module have the following code:
Option Explicit
Public Sub Test()
If ThisWorkbook.NoValues Then
ThisWorkbook.FillValues "First Value", "Second Value"
End If
Debug.Print CStr(ThisWorkbook.Count) & " values defined."
Test_Global_Var 0
Test_Global_Var 1
End Sub
Public Sub Test_Global_Var(ByVal index As Long)
' Part of a UDF
Debug.Print "ThisWorkbook.Position(" & CStr(index) & ")"
Debug.Print ThisWorkbook.Position(index)
End Sub
In ThisWorkbook have the following code:
Option Explicit
Private m_position() As Variant
Private Sub Workbook_Open()
Call DefaultValues
End Sub
Public Property Get Position(ByVal index As Long) As Variant
Position = m_position(index)
End Property
Public Sub DefaultValues()
m_position = Array("First", "Second")
End Sub
Public Sub FillValues(ParamArray args() As Variant)
m_position = args
End Sub
Public Property Get Count() As Long
Count = UBound(m_position) - LBound(m_position) + 1
End Property
Public Property Get NoValues() As Boolean
On Error GoTo ArrUndefined:
Dim n As Long
n = UBound(m_position)
NoValues = False
On Error GoTo 0
Exit Sub
ArrUndefined:
NoValues = True
On Error GoTo 0
End Property
PS. In VBA never use Integer, but instead use Long. Integer is a 16bit type, while Long is the standard 32bit type that all other programming languages consider as an integer.

Answer 2

It is possible to consider a global dictionary variable and pass data through it from the UDF.
First add reference to Microsoft Scripting Runtime:
Thus, build the dictionary like this:
Public myDictionary As Dictionary
To initialize the myDictionary variable, consider adding it to a Workbook_Open event:
Private Sub Workbook_Open()
Set myDictionary = New Dictionary
End Sub
Then the UDF would look like this:
Public Function FillDicitonary(myVal As Long) As String
If myDictionary.Exists(myVal) Then
myDictionary(myVal) = "position " & myVal
Else
myDictionary.Add myVal, "position " & myVal
End If
FillDicitonary = "Filled with " & myVal
End Function
And it would overwrite every key in the dictionary, if it exists. At the end, the values could be printed:
Public Sub PrintDictionary()
Dim myKey As Variant
For Each myKey In myDictionary
Debug.Print myDictionary(myKey)
Next
End Sub