On 5 Feb, 18:00, Dave Peterson wrote:
What do you mean by an error code? *

Do you mean the err.number? *If yes, then you have to do something special since
err.numbers would be the sqareroot of a number.

Maybe you could do something like:

[..]
Hi, Dave,

thanks for the suggestion. However, my actual function MyFun is more
complex than MySqrt, which was just an example, and can assume
negative values. So the caller cannot understand if something went
wrong, by looking at the sign of the result.

Or you could pass the error object, too:

Option Explicit
Function mySqrt(x As Double, myError As ErrObject) As Double

* * Dim myVal As Variant
* * On Error Resume Next
* * myVal = Sqr(x)
* * If Err.Number < 0 Then
* * * * Set myError = Err
* * * * mySqrt = -1
* * Else
* * * * mySqrt = myVal
* * End If

End Function
Sub testme()

* * Dim res As Double
* * Dim myRetError As ErrObject

* * res = mySqrt(-1, myRetError)

* * If res = -1 Then
* * * * With myRetError
* * * * * * MsgBox .Number & vbLf & .Description
* * * * End With
* * Else
* * * * MsgBox res
* * End If

End Sub


Again, this doesn't work because it relies on checking the sign of
MySqrt. Can you suggest a workaround? Maybe I could substitute

* * If res = -1 Then

with

* * If Not myRetError Is Nothing Then

BTW, your example is very interesting because it shows that I didn't
understand something about VBA functions. I thought that VBA functions
couldn't pass back any argument apart from the function value, and, as
a matter of fact, when I tried doing the same declaring myRetError As
Boolean, I got a compile time error. So I thought that wouldn't work
even when using Object variables. This is false, though, because your
code works perfectly. Is there some special rule about Object
variables which make them behave differently than other variables,
when passed to/from functions? Thanks,

Best Regards

Sergio Rossi (deltaquattro)





deltaquattro wrote:

Hi,

after some discussions on the ng I decided to keep input data checking
inside my functions. This prompts the problem of how to return an
error code from the function: for example

Function MySqrt(x as Double) As Double
Dim err As Boolean
If x <0 Ihen
* err=True
* Exit Function
Else
*err=False
*x = Application.Worksheetfunction.sqrt(x)
End If
End Function

However, err cannot be passed back to the caller! I've read about
different workarounds, and I would like to know your opinion on them,
or just which is your approach:

1. convert *the Function to a Sub (easiest, but maybe slower?)
2. pass err ByRef (best?)
3. declare Function As Variant. Variant variables, however, cause a
slowdown of the code, so would this be any faster than 1. ?
4. use global variables (I'd rather not).

Thanks in advance,

Best Regards,

Sergio Rossi

--

Dave Peterson