I have an XSUB that returns a list of things like this:
void
foo()
PPCODE:
{
EXTEND(SP, 2);
PUSHs(sv_2mortal(newSViv(42)));
PUSHs(sv_2mortal(newSVpvn("Forty-two", 9)));
XSRETURN(2);
}
It works fine as it is, but I though that the following might be a
little easier on the eye:
void
foo()
PPCODE:
{
EXTEND(SP, 2);
PUSHi(42);
PUSHp("Forty-two", 9);
XSRETURN(2);
}
However, when I try to build the latter I get this compiler error:
'targ' : undeclared identifier
Having hunted around a bit for examples of other things using PUSHi()
and PUSHp(), I found that the constant() XSUB in a typical
"const-xs.inc" file produed by ExtUtils::Constants contains a PREINIT:
section like this:
PREINIT:
#ifdef dXSTARG
dXSTARG; /* Faster if we have it. */
#else
dTARGET;
#endif
and sure enough, if I add that to my XSUB then it builds and works OK
once more.
Why is this necessary, and how was I supposed to know it? Neither
dTARGET nor dXSTARG seem to be documented anywhere, and there is no
mention of the need for such things in the documentation of PUSHi() etc.
Aside from all that, is the PUSHi()/PUSHp() example above OK? It
doesn't appear to leak, but I'm always wary of removing calls to
sv_2mortal(). I seem to recall that the "targ" stuff has a different
"mortality" scheme relating to the OP tree, but I'm not sure.
- Steve
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