On Tue, 10 Mar 1998, Richard Houldsworth wrote:
> The ListGroup GetCellItem action can place NULL in an ObjectRefVar.
> The example above declares an invalid initial contents to an
> ObjectRefVar, and presumably the same could occur for
> ContentRefVars. Section 50.3 and 50.4 seem to indicate that
> in these cases the variable contents should be set to NULL.
>
> However, the definitions for ObjectRefVar/ContentRefVar don't
> indicate that the Value attribute can take NULL. But also, there
> is no way to test a reference against NULL. This seems to be a
> significant ommision. Shouldn't TestVariable include an isNull
> operator for reference types?
Some time ago I complained about the (inconsistent) usage of NULL. It suggests
an implementation method, but imho it should be read as "the internal
representation of the null-value". This could be, for example, encoded as
'( "" 0)'. The usage of 'NULL' somehow suggests the usage of a null-pointer
representation ('char * 0').
So, it should be at least a valid ObjectReference. This way, there would be
no problem with the TestVariable action.
What do you think?
Andreas
-- o _ Andreas Kraft (\_|_) GMD FOKUS, kraft@fokus.gmd.de, +49 30 3463-7232 T> ] [ The sky is the limit