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Postings from October 2000
On Thu, Oct 05, 2000 at 07:26:38AM -0500, Jarkko Hietaniemi wrote:
> Yup, seems like it becomes an NV. Grr. It must be using
> some other routine than is being used in parse time since
At run-time, it doesn't use *any* routine. That's what I was complaining
about, roughly. You come into pp_add with two SVs. Let's say you're doing
$a = "123foo"; $b = 3;
then our SVs, sitting on the top of the stack, would look like:
SV = IV(0x80fdc24) at 0x80fcf28
REFCNT = 1
FLAGS = (IOK,pIOK)
IV = 3
and
SV = PV(0x80f31c4) at 0x80fcf30
REFCNT = 1
FLAGS = (POK,pPOK)
PV = 0x8101b40 "123foo"\0
CUR = 6
LEN = 7
Now look what happens to the stack:
PP(pp_add)
{
djSP; dATARGET; tryAMAGICbin(add,opASSIGN);
{
dPOPTOPnnrl_ul;
Here, two NVs are popped off; so Perl calls SvNV on the two topmost
SVs, whatever they are, which will convert them into NVs, whether we
want it or not.
SETn( left + right );
Then the NVs are added and the sum is put back on the top.
--
A list is only as strong as its weakest link.
-- Don Knuth
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