topic isNothing in VBA for AutoCAD R14 in VBA Forum

isNothing in VBA for AutoCAD R14

Anonymous — Thu, 04 Nov 1999 13:40:30 GMT

Hello,

I want to test an Objectvariable in AutoCAD whether it is Nothing or it
contains data.

But my VBA in AutoCAD R14 doesn't know the method "isNothing()".

Is there any other possibility to check this out?

Thanks,
Stephan Bulheller

Re: isNothing in VBA for AutoCAD R14

Anonymous — Thu, 04 Nov 1999 13:40:30 GMT

Re: isNothing in VBA for AutoCAD R14

Anonymous — Thu, 04 Nov 1999 14:27:31 GMT

It's two words:

If Something Is Nothing Then
else
endif

Mark Holder

Stephan Bulheller wrote:

> Hello,
>
> I want to test an Objectvariable in AutoCAD whether it is Nothing or it
> contains data.
>
> But my VBA in AutoCAD R14 doesn't know the method "isNothing()".
>
> Is there any other possibility to check this out?
>
> Thanks,
> Stephan Bulheller

Re:

Anonymous — Thu, 04 Nov 1999 18:54:09 GMT

Stephan and Mark,

A little extra, and correct me if I'm wrong:

If Object Is Nothing Then
'the object has NOT been created using Set Object = Whatever, this will
return true. It does not indicate that the object has nothing in it.
'if the object has been created and has nothing in it, this will be
false, because it has been created with Set.
'if the object contains things this will also be false, not because it
contains things, but because it has been created.
End If

If Object.Count = 0 Then
'the object has been created using Set Object = Whatever, and it actually
contains nothing. This statement will
'generate an error if the object has not been created with Set.
End If

-Danny Polkinhorn
SRSS & Associates, Inc.
Atlanta, GA

Mark Holder wrote:

> It's two words:
>
> If Something Is Nothing Then
> else
> endif
>
> Mark Holder
>
> Stephan Bulheller wrote:
>
> > Hello,
> >
> > I want to test an Objectvariable in AutoCAD whether it is Nothing or it
> > contains data.
> >
> > But my VBA in AutoCAD R14 doesn't know the method "isNothing()".
> >
> > Is there any other possibility to check this out?
> >
> > Thanks,
> > Stephan Bulheller

Re:

Anonymous — Thu, 04 Nov 1999 21:15:14 GMT

Danny,

I think your comments are mostly true, but you seem to be confusing the generic
object - type variable with a collection - type object. In general, objects don't
have a Count property. As you say, a collection object can be Not Nothing (Set
myCol = New Collection), and still have no items in it (myCollection.Count=0).
Any object defined by a class module, even if it has been "instantiated" by a Set
statement, will raise an error on myObject.Count unless the class is designed to
have the Count property.

Mark Holder

Danny Polkinhorn wrote:

> Stephan and Mark,
>
> A little extra, and correct me if I'm wrong:
>
> If Object Is Nothing Then
> 'the object has NOT been created using Set Object = Whatever, this will
> return true. It does not indicate that the object has nothing in it.
> 'if the object has been created and has nothing in it, this will be
> false, because it has been created with Set.
> 'if the object contains things this will also be false, not because it
> contains things, but because it has been created.
> End If
>
> If Object.Count = 0 Then
> 'the object has been created using Set Object = Whatever, and it actually
> contains nothing. This statement will
> 'generate an error if the object has not been created with Set.
> End If
>
> -Danny Polkinhorn
> SRSS & Associates, Inc.
> Atlanta, Ga

Re:

Anonymous — Thu, 04 Nov 1999 23:24:17 GMT

From the Visual Basic help Files of VB Design
http://vbdesign.hypermart.net/cadpages/

Hi all,
Wow, that's a lot about Nothing! If I may . .

The Nothing Keyword is used only with Object variables to determine if a
variable has a valid object reference

If objLlama Is Not Nothing Then

or you can use it to destroy a current object reference

Set objLlama = Nothing

You see when you first declare an object variable it contains a special
value - Nothing

So when an Object is set to something, its Not Nothing anymore

hehe
Randall Rath
VB Design

Re:

Anonymous — Fri, 05 Nov 1999 09:51:59 GMT

Thanks to all. It works...

Nice feature you must take "Is Nothing" instead of "IsNothing".
Because in the Online-Documentation of VBA you only find a hint to
"ISNothing".

Thanks,
Stephan Bulheller

Re:

Anonymous — Mon, 08 Nov 1999 21:31:59 GMT

Mark,

I stand corrected. I think I was making an assumption from Stephan's post where he
wanted to know if his object "contained data." I assumed he meant a collection.

-Danny

Mark Holder wrote:

> Danny,
>
> I think your comments are mostly true, but you seem to be confusing the generic
> object - type variable with a collection - type object. In general, objects don't
> have a Count property. As you say, a collection object can be Not Nothing (Set
> myCol = New Collection), and still have no items in it (myCollection.Count=0).
> Any object defined by a class module, even if it has been "instantiated" by a Set
> statement, will raise an error on myObject.Count unless the class is designed to
> have the Count property.
>
> Mark Holder
>
> Danny Polkinhorn wrote:
>
> > Stephan and Mark,
> >
> > A little extra, and correct me if I'm wrong:
> >
> > If Object Is Nothing Then
> > 'the object has NOT been created using Set Object = Whatever, this will
> > return true. It does not indicate that the object has nothing in it.
> > 'if the object has been created and has nothing in it, this will be
> > false, because it has been created with Set.
> > 'if the object contains things this will also be false, not because it
> > contains things, but because it has been created.
> > End If
> >
> > If Object.Count = 0 Then
> > 'the object has been created using Set Object = Whatever, and it actually
> > contains nothing. This statement will
> > 'generate an error if the object has not been created with Set.
> > End If
> >
> > -Danny Polkinhorn
> > SRSS & Associates, Inc.
> > Atlanta, Ga