Thats a good point tom. In fact, null can be kind of like a special "state"
- certainly with databases it is.
Keep the thoughts coming please.
On 3/16/07, Tom Gonzalez <tomgon(a)nortel.com> wrote:
We handle it as it can't be anything else but null cause null is returned
when an access fails or some error occurs. This keeps it from falling into a
valid evaluation and possibly a subtle bug going uncaught.
Tom G
------------------------------
*From:* rules-dev-bounces(a)lists.jboss.org [mailto:
rules-dev-bounces(a)lists.jboss.org] *On Behalf Of *Mark Proctor
*Sent:* Thursday, March 15, 2007 12:42 PM
*To:* Rules Dev List
*Subject:* Re: [rules-dev] need advice re null handling
Its not about giving it up, its how we handle when those fields are null,
do we treat it like a primitive and assume its 0, or do we say it can't be
equal to anything else but null.
In the following example neither y or z is defined, thus y is null and z
is 0;
int x = 0;
Integer y;
in z;
x == y // is false;
x == z // is true
y == null // is true
Mark
Tom Gonzalez wrote:
The flexibility provided by an Object is very valuable. We use Integer and
String objects all over the place today in our facts with drools. I would
hate to give it up.
Tom G
------------------------------
*From:* rules-dev-bounces(a)lists.jboss.org [
mailto:rules-dev-bounces@lists.jboss.org<rules-dev-bounces@lists.jboss.org>]
*On Behalf Of *Mark Proctor
*Sent:* Thursday, March 15, 2007 6:29 AM
*To:* Rules Dev List
*Subject:* Re: [rules-dev] need advice re null handling
if bar is an integer it will be 0, if its an Integer it will be null. The
Q is do we make Integer work like the primitive, or do we make it work like
an Object.
Mark
Michael Neale wrote:
http://jira.jboss.com/jira/browse/JBRULES-627
OK, this much is clear:
Foo(field == null) can be true if field is null.
but, what about Foo(field > 3), and field is null? should that be false?
what about Foo(field != 3) - should that be true?
in SQL, null will always result in a false condition, unless you
explicitly use null.
Thoughts?
Michael.
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