On Tue, Dec 14, 2004 at 08:15:29AM +0000, Sisyphus wrote:
> I reckon I'll understand this better when (if ever) I understand how
> overload.pm creates the PL_sv_yes (or PL_sv_no, as the case may be) and
> sends it to the overload subroutine as the third argument.
I think that you can do them in perl space as the result of boolean operations.
For example:
$ perl -MDevel::Peek -e '$a=\(1==1); Dump $a'
SV = RV(0x811438) at 0x808c3c
REFCNT = 1
FLAGS = (ROK)
RV = 0xf6ab0
SV = PVNV(0x800e30) at 0xf6ab0
REFCNT = -2147483648
FLAGS = (IOK,NOK,POK,READONLY,pIOK,pNOK,pPOK)
IV = 1
NV = 1
PV = 0x3001b0 "1"\0
CUR = 1
LEN = 2
I seem to be able to get a reference to PL_sv_yes into $a, and I believe that
you can check the reference addresses with == to see if you have the real
thing:
$ perl -le '$yes=\(1==1); $a=\(!!1); $t = 1 == 1; $b = \$t; foreach (qw(a b))
{print "$_: $$_: ", $$_ == $yes ? "PL_sv_yes" : "not"}'
a: SCALAR(0xf6ab0): PL_sv_yes
b: SCALAR(0x808c90): not
So $a is a reference to PL_sv_yes, and $b is merely a reference to something
truthful.
I think that that negative reference count on PL_sv_yes may be a bug.
Nicholas Clark
