Got a function:
================================================== ===============
Public Function ResetDateFirst_GetOrCompute( _
ByVal
theCouponResetFrequencyID As Long, _
ByVal theIssueDate As
Date, _
ByVal theSecurityID
As Long, _
ByVal theWorkSwitch
As Boolean, _
Optional ByVal
theSettlementDate As Date _
) As Variant
================================================== ===============

When calling the function as in:
================================================== ===============
?ResetDateFirst_GetOrCompute(12,#10/21/2011#,25431,False)
================================================== ===============

I get
==============================
?ismissing(theSettlementDate)
False
==============================

But I have not passed anything.

In fact, IsDate(theSettlementDate) = True, and if I operate
using theSettlementDate, it actually works as if I had passed a
date of "12:00:00 AM".

I must be doing something wrong....

But what?
--
PeteCresswell

"(PeteCresswell)" <x@y.Invalid> wrote

The IsMissing function can only be used with variant data types. That's
because variants have a 'missing' flag bit and ordinary types don't.

So you can either declare theSettlementDate as variant and use IsMissing to
check for existence, then convert to date using the Cdate function

or:

Set a default value of (say) 01/01/1980 and check for that. If you get a
hit, the argument is missing:

Optional theSettlementDate As Date = "01/01/1980"

Per Stuart McCall:
I went with the Variant data type and all is well.

Thanks!... I never, ever would have doped that one out on my own.
--
PeteCresswell