At 02:30 PM 4/17/2002 -0400, Dan Champion wrote:
>Since my upgrade from 6.5win to 6.5++ I have a problem I can't
>seem to debug. In the code below (an exit eep from the second
>field of a form) the first part (where invqty = 0) works great and
>DOES skip to invbin1. the secont part (where invqty <> 0) does
>everything except skip to invbin1. INstead, after the load table,
>and resetting the variable, it just sits there and no amount of tab,
>enter, or space will bring you focus to the form. Any Ideas what
>I have done wrong?
Dan,
What is the SETting for EQNULL?
Using The Glorious R:BASE 2000 (ver 6.5++), Build:1.842xRT03
and higher, following is the technical explanation and correct
evaluation of expressions when EQNULL is SET to ON.
R:BASE uses special processing on simple IF commands for
maximum speed. However, the way these were processed was
not consistent with the way complex IF commands or WHILE
commands were processed with regard to comparisons using
NULL values. The EQNULL setting at TRUE means that a
comparison between two NULL values is a match and that a
comparison between a NULL value and a non-NULL value is
not. When EQNULL is set to FALSE then a comparison
between two NULL values is not a match nor is a comparison
between a NULL value and a non-NULL value a mismatch.
The NULL value essentially make the whole thing "unknown'.
This behavior was followed in WHILE and complex IF
commands but was not followed in simple IF commands. A
simple IF command has only one comparison and the left
side is a simple variable and the right side is either a variable
or a constant. A simple IF does not have any expressions.
Compare these code samples:
SET VAR v1 TEXT = NULL
SET VAR v2 TEXT = NULL
SET EQNULL OFF
IF v1 = .v2 THEN
-- will not be a hit
ENDIF
IF v1 <> .v2 THEN
-- will not be a hit
ENDIF
IF v1 <> 'This' THEN
-- will not be a hit (it used to be before this fix)
ENDIF
SET EQNULL ON
IF v1 = .v2 THEN
-- will be a hit
ENDIF
IF v1 <> .v2 THEN
-- will not be a hit
ENDIF
IF v1 <> 'This' THEN
-- will be a hit
ENDIF
Before this fix, the comparison "IF v1 <> 'This' THEN" would be
a hit with EQNULL set ON or FALSE when it should only be a
hit when EQNULL is ON. This means that now:
"IF (.v1) <> 'This' THEN" and "IF v1 <> 'This' THEN"
will both process the same way. In the past they would be
different because of this problem.
In your code if you want the comparison of a NULL variable
and a non-NULL constant to be a hit then you should run
with EQNULL set ON.
Hope that helps!
Enjoy and make sure to have fun!
Very Best Regards,
Razzak.
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