Is there a way to execute VBA code contained in a cell? - vba

Question

I'm building a macro in Excelto run rules against a set of data and output whether each row passes or fails the rules. I want to be able to add, remove, or alter the rules without altering the macro. As such I have a DATA worksheet and a RULES worksheet and the macro generates the OUTPUT worksheet and then populates it.
RULES is set up so that each different rule is enumerated on a different row. For this to work I need to be able to enter the actual VBA code relevant to the rule in on RULES, then I need to have the macro look at that column on RULES and execute the code in the cell.
Simplified example of my setup-
DATA has : ID, Dividend1, Dividend2, Divisor. There are n rows on DATA.
An example of a row on DATA might be ID="123", Dividend1=5, Dividend2=7, Divisor=35.
RULES has : Name, Formula, Threshold. For simplicity's sake there is only .
Let's set the as Name="Example", Formula=[see below], Threshold="0.15" (Threshold is used for conditional formatting in the macro, in this example it is unused.)
I'm going to use pseudocode for Formula just to eliminate the need to explain some of the irrelevant particulars of my macro so far. RULES.Formula should contain a line of VBA code that carries out-
If CurrentDATARow.Dividend1 = Empty Then
CurrentDATARow.Dividend2 / CurrentDATARow.Divisor
Else
CurrentDATARow.Dividend1 / CurrentDATARow.Divisor
End If
So, all of this explanation just to give context to this question: What can I do in the VBA of the macro to make it read the contents of RULES.Formula and make it execute that code inline with the rest of the macro?

Answer 1

If you have (say)
IF({dividend1}="",{dividend2}/{divisor},{dividend1}/{divisor})
stored in a "rule" cell (note do not include the "="), you can use Replace() to replace the placeholders with the relevant cell addresses for each cell in the row you're checking.
Then use something like
Dim val
val=Sheet1.Evaluate(yourformulastring) 'evaluate vs. specific worksheet
If Not IsError(val) Then
'check against thresholds etc
End If
If the evaluation results in an error you can test with IsError(val) as shown, otherwise it will return the result of the formula, which you can test against your "threshold" value cell. If you set background colors on your threshold cells you can color each row according to which threshold was exceeded.
NOTE without a worksheet qualifier, Evaluate will calculate the formula based on the ActiveSheet, so make sure the right sheet is active when this runs if you don't use the qualifier.

Answer 2

you could store your Tests/Rules as Excel worksheet formulas in Named ranges. Then you just call them from the cells.
see Ozgrid: Named Formulas
If you give us some example data and the type of calculations or rules I can give you a couple of examples.