Some examples of how to avoid select
Use Dim
'd variables
Dim rng as Range
Set
the variable to the required range. There are many ways to refer to a single-cell range:
Set rng = Range("A1")
Set rng = Cells(1, 1)
Set rng = Range("NamedRange")
Or a multi-cell range:
Set rng = Range("A1:B10")
Set rng = Range("A1", "B10")
Set rng = Range(Cells(1, 1), Cells(10, 2))
Set rng = Range("AnotherNamedRange")
Set rng = Range("A1").Resize(10, 2)
You can use the shortcut to the Evaluate
method, but this is less efficient and should generally be avoided in production code.
Set rng = [A1]
Set rng = [A1:B10]
All the above examples refer to cells on the active sheet. Unless you specifically want to work only with the active sheet, it is better to Dim a Worksheet
variable too:
Dim ws As Worksheet
Set ws = Worksheets("Sheet1")
Set rng = ws.Cells(1, 1)
With ws
Set rng = .Range(.Cells(1, 1), .Cells(2, 10))
End With
If you do want to work with the ActiveSheet
, for clarity it's best to be explicit. But take care, as some Worksheet
methods change the active sheet.
Set rng = ActiveSheet.Range("A1")
Again, this refers to the active workbook. Unless you specifically want to work only with the ActiveWorkbook
or ThisWorkbook
, it is better to Dim a Workbook
variable too.
Dim wb As Workbook
Set wb = Application.Workbooks("Book1")
Set rng = wb.Worksheets("Sheet1").Range("A1")
If you do want to work with the ActiveWorkbook
, for clarity it's best to be explicit. But take care, as many WorkBook
methods change the active book.
Set rng = ActiveWorkbook.Worksheets("Sheet1").Range("A1")
You can also use the ThisWorkbook
object to refer to the book containing the running code.
Set rng = ThisWorkbook.Worksheets("Sheet1").Range("A1")
A common (bad) piece of code is to open a book, get some data then close again
This is bad:
Sub foo()
Dim v as Variant
Workbooks("Book1.xlsx").Sheets(1).Range("A1").Clear
Workbooks.Open("C:\Path\To\SomeClosedBook.xlsx")
v = ActiveWorkbook.Sheets(1).Range("A1").Value
Workbooks("SomeAlreadyOpenBook.xlsx").Activate
ActiveWorkbook.Sheets("SomeSheet").Range("A1").Value = v
Workbooks(2).Activate
ActiveWorkbook.Close()
End Sub
And it would be better like:
Sub foo()
Dim v as Variant
Dim wb1 as Workbook
Dim wb2 as Workbook
Set wb1 = Workbooks("SomeAlreadyOpenBook.xlsx")
Set wb2 = Workbooks.Open("C:\Path\To\SomeClosedBook.xlsx")
v = wb2.Sheets("SomeSheet").Range("A1").Value
wb1.Sheets("SomeOtherSheet").Range("A1").Value = v
wb2.Close()
End Sub
Pass ranges to your Sub
s and Function
s as Range variables:
Sub ClearRange(r as Range)
r.ClearContents
'....
End Sub
Sub MyMacro()
Dim rng as Range
Set rng = ThisWorkbook.Worksheets("SomeSheet").Range("A1:B10")
ClearRange rng
End Sub
You should also apply Methods (such as Find
and Copy
) to variables:
Dim rng1 As Range
Dim rng2 As Range
Set rng1 = ThisWorkbook.Worksheets("SomeSheet").Range("A1:A10")
Set rng2 = ThisWorkbook.Worksheets("SomeSheet").Range("B1:B10")
rng1.Copy rng2
If you are looping over a range of cells it is often better (faster) to copy the range values to a variant array first and loop over that:
Dim dat As Variant
Dim rng As Range
Dim i As Long
Set rng = ThisWorkbook.Worksheets("SomeSheet").Range("A1:A10000")
dat = rng.Value ' dat is now array (1 to 10000, 1 to 1)
for i = LBound(dat, 1) to UBound(dat, 1)
dat(i,1) = dat(i, 1) * 10 ' Or whatever operation you need to perform
next
rng.Value = dat ' put new values back on sheet
This is a small taster for what's possible.
Best Answer
I discovered the exact problem but I want to up-vote you all for trying to help me figure this out, and give GSerg the credit because, while I wasn't completely out of luck, he was dead on with his suggestion that
Good find GSerg.
The problem was with Event Handlers. The workbook contains a series of event handlers like Workbook_Open, Worksheet_Change, etc. Every now and then, one of the actions taken by these event handlers will cause some cells in the workbook to recalculate. If excel triggers a recalculation while a macro is running, any cells containing this UDF will result in an error. This is because for some reason, during the VBA triggered recalculation, the .HasFormula property was unavailable, just like @GSerg said:
Presumably - the next bit is an oversight on Excel's part, but once the macro is done running, if a recalculation has been done, resulting in errors because UDFs didn't run properly, excel will not try to run the UDFs again. The resulting error value will be assumed to be the return value of the call, and will not change unless it thinks the parameter to that UDF has changed. Excel will cache the result of the User Defined Function call until the cell its parameter references is changed.
That is why stepping through 'Evaluate Formula' will show everything working until the very last step, where it doesn't actually evaluate the last step, it just shows the value from the spreadsheet as was last calculated.
Solution
There were actually two possible solutions. The first solution I found was to disable automatic calculation at the beginning the Event Handlers, and re-enable it afterwards. For some reason, even though a macro is running at the time calculation is set back to xlCalculationAutomatic, it will cause the UDFs to be successfully re-evaluated, and the property is available.
The second solution, which I prefer because it prevents this from accidentally ever happening again, is to use a different method to check for a formula:
The .Formula property is never unavailable. So this problem never occurs.