We should have 1 recommended way for testing NULL registers.
If we support get_bool() then lets make sure it works for REAL NULL
pmc registers as well as PMCNULL.
If not, code will appear to work correctly on a "safe" core
but will seg fault on some other. Also, I see no reason not
to use PMCNULL in all cores now.
-Melvin
Leopold Toetsch <[EMAIL PROTECTED]>
12/03/2003 10:43 AM
Please respond to lt
To: [EMAIL PROTECTED] (Juergen Boemmels)
cc: [EMAIL PROTECTED]
Subject: Re: [RfC] Testing for null
Juergen Boemmels <[EMAIL PROTECTED]> wrote:
> Hi,
> I'm curently playing around with open calls returning a PMCNULL
> instead of a half valid IO-Object. But the main problem with that is
> that there is currently no way for the byte-code to detect such a
> case.
C<defined> tests for PMCNULL too and is usable.
> * A PMCNULL has false semantics. This may be done by letting
> get_boolean return FALSE, or by adding a test to if_p_ic op:
> if(!PMC_IS_NULL($1) && $1->vtable->get_boolean($1))
Or the null.pmc gets a valid get_bool() vtable slot returning 0.
OTOH when PMCNULL is a real NULL, this will fail then.
> * Have a special op for this if_null and unless_null which exlusively
> test for NULL.
Probably better.
> boe
leo
