Can you access a VBA list with an in-cell Excel formula? - excel

Question

I wrote a VBA script/macro which runs when a change is detected in a specific range (n x m) of cells. Then, it changes the values in another range (n x 1) based on what is detected in the first range.
This bit works perfectly ... but then comes the age old erased undo stack problem. Unfortunately, the ability for the user to undo their last ~10 or so actions is required.
My understanding is that the undo stack is only cleared when VBA directly edits something on the sheet - but it is preserved if the VBA is just running in the back without editing the sheet.
So my question is: Is it possible to use an in cell formula (something like below) to pull values from a VBA array?
'sample of in-cell function in cell A3
=function_to_get_value_from_vba_array(vba_array, index_of_desired_value)
Essentially, VBA would store a 1D array of strings with the values needed for the range. And by using a formula to grab the value from the array: I might be able to get around the issue of the undo stack being erased.
Thanks!

Answer 1

Solution
You need to do something like the following: your argument for the function should be calling the array bulding; I created one dummy function that creates some sample arrays to demonstrate it. In your case, likely you will need to store the changes on the worksheet event in a global array variable instead, and as you stated, do nothing on the worksheet (whenever a change happens, just redim or appended it on your global array as needed). However, a new problem may arise and that is when you close/reopen, or by some reason the array is lost, so you need to keep track of it, I would suggest to catch before close event and then convert the formulas to static values.
Function vba_array(TxtCase As String)
Dim ArrDummy(1) As Variant
Select Case TxtCase
Case "Txt": ArrDummy(0) = "Hi": ArrDummy(1) = "Hey"
Case "Long": ArrDummy(0) = 0: ArrDummy(1) = 1
Case "Boolean": ArrDummy(0) = True: ArrDummy(1) = False
End Select
vba_array = ArrDummy
End Function
In your calling function, do the following
Function get_value_from_vba_array(vba_array() As Variant, index_of_desired_value As Long) As Variant
'when parsing, even with option base 0 it starts at 1, so we need to add 1 up
get_value_from_vba_array = vba_array(index_of_desired_value + 1)
End Function
In your book, your formula should be something like:
=get_value_from_vba_array(vba_array("Txt"),1)
Demo
I did some actions before, so you are able to see that the "undo" works