Workaround for Excel 2002/2003 UDFs recalculating and changing cel

[Ed Fulda]

Hello
I have been asked to look at moving a very large set of pricing sheets from
Excel 2000 to Excel 2003. In the progress of this I have found that the
functionality for a UDF in a cell to change/recalculate any other cells has
been removed in Excel XP, whereas it was available in Excel 2000. The amount
of work required to refactor the code is very large, and before starting on
it it would be good to find out if there is a workaround. The Sheet works in
the following way:
-User enters values, clicks a button to run a Macro,
-Macro calculates all the ranges required to return a price
-In many of the cells it is calculating are Functions which go and look at a
large number of cells to calculate the price, sometimes writing to other
Cells and sometimes having to recalculate other cells
-As it is such a large sheet we can't simply calculate all cells before we
tell it to price, as they are not all needed and so aren't calculated unless
needed for performance reasons.

It would be a lot of work to move the functionality from the Functions to
the initial macro call, though this would solve the problem. Is there any
other workaround?

Macro security is set to low.

The Errors I receive are the following:

The UDF will hit a line like Range("DataRange").Calculate and this will
raise a "Calculate method of Range class Failed" error.
If it hits a line like Range("DataRange").Value = 1 this will raise a
"Application-defined or object-defined error"
If it hits a line like ActiveWorkbook.Names.Add Name:="This_Name",
RefersToR1C1:="=Sheet1!R8C2" then it also raise a "Application-defined or
object-defined error".

Any of these run from a UDF in Excel 2000 works.

I have a sample workbook if this isn't clear

 

[Niek Otten]

Hi Ed,

I'm pretty sure that changing cells from a UDF that was called (directly or
indirectly) from a worksheet has not been possible in any version of Excel.
Please send me your sample workbook

 

[Peter T]

First port of call is Charles Williams' site, this page for starters -
http://www.decisionmodels.com/calcsecretsj.htm

Whilst there are differences in the way Excel versions handle UDFs, from the
information you have given I suspect the problems are not related to version
but something else. I could be wrong but post code with sufficient
information to allow others to reproduce the errors.

Regards,
Peter T

 

[Joel]

I would gete all the errors resolved and see how long it takes for the macro
to run before I make a decision to change the UDF functions.

The line below works in a new workbook in excel 2003

ActiveWorkbook.Names.Add Name:="This_Name", _
RefersToR1C1:="=Sheet1!R8C2"

I had to add a line continuation character to get the above line to run
without a compiler error.

It also runs multiples times without an error which indicates that It
Doesn't matter if the name already exists.

My suspect that you are having problems with which object is the active
object. For some reason the assumptions in excel 2000 and excel 2003 is
using as the default object has changed. Try run the macro with diffferent
worksheets as the activeworksheet and see if you can get the macro to run.
fix the problems one att a time until you get the entire macro to run.

 

[Ed Fulda]

Joel - That line works fine when called as a macro, but not from a function
running in a Cell. My sample code looks like the following:

Function TestFunc() As String
On Error GoTo err
ActiveWorkbook.Names.Add Name:="This_Name", _
RefersToR1C1:="=Sheet1!R8C2"
ActiveWorkbook.Worksheets("Sheet1").Range("WriteCell").Value = "Written"
ActiveWorkbook.Worksheets("Sheet1").Range("RecalcCell").Calculate
TestFunc = "Result"
Exit Function
err: MsgBox err.Description
End Function

Function test2() As String
test2 = Rnd
End Function

Sub calculatesheet()
ActiveWorkbook.Worksheets("Sheet1").Range("CalculatingFunc").Calculate
End Sub

CalculatingFunc is a single cell containing =testfunc()
WriteCell is a single empty cell
RecalcCell contains =test2()

There is then a button which runs calculatesheet

Thanks,
Ed

 

[Peter T]

I missed what you said about expecting the UDF to do things like add Names
and the like. That would not have worked in any version (without some kludge
type workarounds). A UDF called from the worksheet can only return a value
or an array of values.

Peter T

 

[Ed Fulda]

Hi Peter,
It doesn't work in 2003 or XP, but it does work absolutely fine in 2000 - if
you have it installed check with the code I posted in reply to Joel

Ed

 

[Joel]

A UDF can read data from any place. It can only return values to the cell
that called it. If you have code like this it should be turned in to Sub's
(not functions). Then call the sub manually from the worksheet menu tools -
Macros - testFunc. Another choice is to use a change event to trigger the
macro to run rather than manually running the macro. I would start by
converting the code to manual initiatated macros. the after yo uget them
working then posibly adding a control button to make it easier to run the
macro.

 

[Jim Cone]

I just tried TestFunc() in Excel 2000 and it throws an error when called from a worksheet cell.
--
Jim Cone
Portland, Oregon USA



"Ed Fulda" <[email protected]>
wrote in message
Hi Peter,
It doesn't work in 2003 or XP, but it does work absolutely fine in 2000 - if
you have it installed check with the code I posted in reply to Joel

Ed

 

[Peter T]

I forgot, in Excel 2000 a UDF can add a Name, it's an oddity fixed in later
versions. However the next line that attempts to write to another cell will
error.

Adding the Name indirectly triggers one of the "kludges" I mentioned, namely
it triggers a recalc (in 2000). Whilst you can take advantage of it, eg to
write to another cell, the UDF also recalc's multiple times, a long loop. To
escape that include something like the following in your function -

Static bExit as Boolean

on error goto errH
if bExit then
bExit = false
exit sub
end if
bExit = True

do stuff to trigger recalc,
but don't write to other cells !!!

done:
bExit = False
exit function
errH:
resume done
end function

' do other stuff in the "kludged" calculate event

This'll tidy up things for 2000, now forget it and don't use it! It won't
work in later versions and should never have worked in earlier versions.

If the overall objective is to write a Name, use a worksheet change event.

Regards,
Peter T