Validate the arguments before use and keep any
error messages short would be my approach.
'--
Function Sludge(postposition as Double, _
speedrating as Double, _
lastouting as String) as Variant
On Error GoTo Toxic

Select Case True
Case postposition 21
Sludge = "Check Post Position"
Exit Function
Case speedrating < 0
Sludge = "Verify Speed Rating"
Exit Function
Case Len(lastouting) 255
Sludge = "One Word Only Please"
Exit Function
End Select

'Do something in the function

Sludge = "Faster Horses Required"
Exit Function
Toxic:
Sludge = "Function Error " & Err.Number
End Function
--
Jim Cone
Portland, Oregon USA
http://www.realezsites.com/bus/primitivesoftware
(Excel Add-ins / Excel Programming)



"Jack Hoxley [MVP]" <Jack Hoxley
wrote in message
Afternoon all,

I've been doing some research into reporting errors in custom Excel
functions to the end user today. I've not really come up with any promising
leads so I was hoping someone frequenting this newsgroup might be able to
point me in the right direction :-)

The primary interest is in increasing the usability of our addin. Currently
it just dumps out a textual error message into the cell (repeated accordingly
if the output is an array) but this looks plain ugly to say the least.
Something friendly and ideally self-explanatory would make everyone happy and
stop the phones ringing off the hook whenever a scary error message appears!

What i'm wondering about is any standardised options for error pop-ups,
highlighting, help file linking, auto-complete type hints as to which
parameter is wrong etc...etc...

Maybe something like the standard Excel feature where it draws a small green
triangle in the upper-left corner that then shows a pop-up menu with details
on the formula error/warning.

Any suggestions?

Thanks in advance,
Jack