read constant from a cell - excel

Question

I am writing a VBA code to read some text files, I would like the file names to be read directly from cells in excel.
I used the following code
Sub ImportFile()
Const textFilePath As String = "C:\Desktop\"
Const textFileName As String = "File1.txt"
Const newTextFileName As String = "NewFile1.txt"
I want to have something like
Sub ImportFile()
Const textFilePath As String = Range("A2").value
Const textFileName As String = Range("A3").value
Const newTextFileName As String = Range("A4").value
I tried different combinations but it does not seem to like the idea of assigning a constant to a cell value, any work around?
Thanks
P.S I don't know how to write the code in a correct way in this website, I tried to add 4 spaces before the code lines but did not seem to work, any idea why?

Answer 1

I don't think you can assign a constant from a range because the range value could change during your code execution. I tried your declarations in this bit of code:
Option Explicit
Sub ImportFile()
Const textFilePath As String = Range("A2").Value
Const textFileName As String = Range("A3").Value
Const newTextFileName As String = Range("A4").Value
End Sub
and on Debug..Compile in the IDE I got this error
If you change your code to
Option Explicit
Sub ImportFile()
Dim textFilePath As String
Dim textFileName As String
Dim newTextFileName As String
textFilePath = Range("A2").Value
textFileName = Range("A3").Value
newTextFileName = Range("A4").Value
End Sub
You'll find it compiles OK.
Unless you're talking "Universal (physical) constants" like PI,c or G for example, constants rarely are constant. I've found that having a named range, possibly on a hidden sheet, and populating a variable from that named range makes for easier maintenance by users with little no VBA experience. Sure, you need to keep track of those "constants" to maintain them but at least you don't need VBA experience to do so.

Answer 2

You can't do that in vba since your constant variables might change. However, I think that you want to declare and initialize your path variables once so that later if you decide to change them you can do that in one place in the same row where the variable was initialized. So If I were you I would use something like
Option Explicit
sub macro()
Dim FILEPATH As String: FILEPATH = Range("A1").Value
MsgBox FILEPATH
end sub