V4MD and NULL values in lists - LINGO developers please comment

[Gregoire William]

yes...I already got the problem...
I compared too string(x[1]) with "<Null>"

but the best issue would be Valentina return VOID instead of <Null>


-----Message d'origine-----
De : valentina-bounces at lists.macserve.net
[mailto:valentina-bounces at lists.macserve.net]De la part de Florian
Bogeschdorfer
Envoye : mardi 23 novembre 2004 12:37
A : 'Valentina Developers'
Objet : V4MD and NULL values in lists - LINGO developers please comment


Hi Ruslan!

I am having a little problem with getting records as lists containing a
<NULL> value. Infact <NULL> is not a valid value for a lingo list.
You can read it, but you can e.g. not compare it:

--x is the getRecordAsPropList value
X=[#myField:<NULL>] --this will not work in the message window, you need to
get it via Valentina

Put x[1]
--<NULL>
--OK

Put x[1]=<Null>
--misplaced operator
Put x[1]="<Null>"
--0

So when you have only the record and no cursor left (like when transferring
the records via Internet, which is where my problem aroused) there is only
one solution:
Put x[1].string="<Null">
--1

However Lingo programmers like to store lists in various ways. I have not
tested famous xtras like vList, but most developers store lists in text
members like:

Member(myListStoreMember).text=myList.string

And later:

myList=member(myListStoreMember).value

Now if the list contains a <Null>, the value of the member will be 0 instead
of a list, the list is "destroyed".
So you actually have to look before storing the list and replace the <Null>
by "<Null>" or VOID for example.

Now this is maybe not a big deal, but the <Null> in a lingo list is simply
not a valid list value, maybe you can change that in the future to VOID
(Valentina 2).
Or how do other Lingo developers feel about that?

Best regards, Florian

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