Access97: Functions cannot return Null???

I am writing a function that returns a TableDef, and when there is no
TableDef to return, I try to return Null. Problem is I get a "Object
required" error when I try to assign Null to the function name.(actual
error message is in Japanese, sorry if the error message is not exactly the
same in English)

Fine. I will just catch the error, and return without assigning anything.
But wait, IsNull() is not correctly detecting what should have been a Null
return value!

The compiler likes my assigning a Null for return. Why doesn't the runtime?

Public Function getTable(thisDB As TableDefs, thisTableName As String) As
tableDef
On Error GoTo getTable_ERROR
Set getTable = thisDB(thisTableName)
Exit Function

getTable_ERROR:
Set getTable = Null
End Function

Jonathan Scott

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I am not sure but try setting the function to Nothing and then check this
with IsObject rather than Null and IsNull().

HTH
Van T. Dinh
MVP (Access)



"Jonathan Scott via AccessMonster.com"
wrote in message news:e63d9bad3599422791df634c4075ec92@AccessMonste r.com...
I am writing a function that returns a TableDef, and when there is no
TableDef to return, I try to return Null. Problem is I get a "Object
required" error when I try to assign Null to the function name.(actual
error message is in Japanese, sorry if the error message is not exactly
the
same in English)

Fine. I will just catch the error, and return without assigning anything.
But wait, IsNull() is not correctly detecting what should have been a Null
return value!

The compiler likes my assigning a Null for return. Why doesn't the
runtime?

Public Function getTable(thisDB As TableDefs, thisTableName As String) As
tableDef
On Error GoTo getTable_ERROR
Set getTable = thisDB(thisTableName)
Exit Function

getTable_ERROR:
Set getTable = Null
End Function

Jonathan Scott

--
Message posted via http://www.accessmonster.com

Jonathan Scott via AccessMonster.com wrote:
I am writing a function that returns a TableDef, and when there is no
TableDef to return, I try to return Null. Problem is I get a "Object
required" error when I try to assign Null to the function name.(actual
error message is in Japanese, sorry if the error message is not
exactly the same in English)

Fine. I will just catch the error, and return without assigning
anything. But wait, IsNull() is not correctly detecting what should
have been a Null return value!

The compiler likes my assigning a Null for return. Why doesn't the
runtime?

Public Function getTable(thisDB As TableDefs, thisTableName As
String) As tableDef
On Error GoTo getTable_ERROR
Set getTable = thisDB(thisTableName)
Exit Function

getTable_ERROR:
Set getTable = Null
End Function

Jonathan Scott

I'm pretty sure that only a function with a return type of variant can
return Null.

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RBrandt at Hunter dot com

I finally got it to work, but I am curious now what the difference could be
between Null and Nothing?

Jonathan Scott

--
Message posted via http://www.accessmonster.com

So Nothing works?

An Object variable (including function returning an Object can be a
"Nothing" but not Null AFAIK since Null is an unassigned *value*.

--
HTH
Van T. Dinh
MVP (Access)




"Jonathan Scott via AccessMonster.com" wrote in
message news:a850a4b6a15449f298ac879c18b4eba7@AccessMonste r.com...
I finally got it to work, but I am curious now what the difference could
be
between Null and Nothing?

Jonathan Scott

--
Message posted via http://www.accessmonster.com

BTW, note the subtle difference in A2000:

'----
public function fn()

end function
'----


?vartype(fn())
0
?isEmpty(fn())
True
?isNull(fn())
False

A97:
? isempty(eval("fn()"))
True
A2000:
isNull(eval("fn()"))
True

In A2000, when a function returns Empty, Eval converts that to Null

(david)


"Jonathan Scott via AccessMonster.com" wrote in
message news:a850a4b6a15449f298ac879c18b4eba7@AccessMonste r.com...
I finally got it to work, but I am curious now what the difference could be
between Null and Nothing?

Jonathan Scott

--
Message posted via http://www.accessmonster.com