VarType constant 10 -- vbError

[vorpal]

In VBS there is a function CVErr
I works like so (using Excel 2003)
Sub Test()
Dim vTest As Variant

vTest = CVErr(0)

Debug.Print CStr(vTest) & vbTab & VarType(vTest) & vbTab &
TypeName(vTest)

End Sub

The output is:
Error 0 10 Error

Although the VarType constant is valid in VBScript, the function is
not.

Does this VarType ever occur in vbScript?
If so, when and how would I find it?

Cheers,
--Vorpal

[Richard Mueller [MVP]]

Vorpal wrote:

My reference shows that VarType = 10 means vbError. CVErr is not available
in VBScript, but in VB6 it creates an error object with the number
specified. However, I don't think error number 0 makes sense. I made a few
attempts in VBScript to get the VarType function to return 10, but failed.

--
Richard Mueller
MVP Directory Services
Hilltop Lab - http://www.rlmueller.net
--

[vorpal]

On Jul 5, 2:40 pm, "Richard Mueller [MVP]" <rlmueller-

nos...@ameritech.nospam.net> wrote:
> My reference shows that VarType = 10 means vbError. CVErr is not available
> in VBScript, but in VB6 it creates an error object with the number
> specified. However, I don't think error number 0 makes sense. I made a few
> attempts in VBScript to get the VarType function to return 10, but failed.
>

My conclusion was that the VarType 10 is there for use by VBA, and
I've used it in Excel UDFs many times. I'm going to conclude that is
has no function in VBS.

I thought perhaps it had a special purpose use, but if an MVP can't
find a use for it, I won't expend any more thought energy on it. :)

I never used it in VB6. Instead, I used Err.Raise.

--Vorpal

[Old Pedant]

> My reference shows that VarType = 10 means vbError. CVErr is not available
> in VBScript, but in VB6 it creates an error object with the number
> specified.

Ummm...I think that technically it does *NOT* create "an error object".

Per the docs:
http://msdn.microsoft.com/en-us/library/aa262707(VS.60).aspx

And I quote:
"Returns a Variant of subtype Error containing an error number specified by
the user."

A Variant is *NOT* an object. It truly is just the fundamental
implementation of a variable. So it's just a block of 16 bytes where the
variant number is a 10 and the value is the given error number. Same as a
block of 16 bytes with a variant number of 3 and a value of 0x00010001 is
seen as a LONG (32-bit integer) with a value of 65537.

And that's the fundamental difference in error handling between VB6 and
VBScript: VBScript really *DOES* use an error *OBJECT*, which is much richer
in implementation than VB6's simple vbError variant.

You *COULD* get a vbError instance in VBScript, by calling a COM component
that returned a VARIANT with the right values in the right spots in the 16
bytes. And I suppose I could even think of instances (VBS calling a COM
component written in VB6) where that might make sense. But of course all
VBScript could do with that variant would be find its VarType and then use
CSTR( ) on it. [I'm pretty sure that VariantChangeTypeEx( ), if asked to
change a vbError variant to a vbString variant would do the same thing the
VB6 does, creating the string
Error NNN
where NNN is the numeric value of the variant.

It's the same principal as having an ADODB.Field object that has a value
that is a decimal variant. VBScript can't handle that particular variant,
but you can call CDBL( ) or CSTR( ) on the value to get it converted to a
variant that VBScript can handle.

[Old Pedant]

So I hadn't worked with Variant in C++ code since 2001 and went to refresh my
memory.

Indeed, VT_ERROR is a standard variant type, with a value that is an SCODE.
And an SCODE uses the same numeric values as HRESULT values. So think of it
as an HRESULT wrapped into a Variant so that it's usable by any COM
component and thus by the scripting languages (as well as VBA and VB6).

But that means that clearly you should be able to do CLNG(x) or CSTR(x)
where x is a VT_ERROR variant.