Re: sv_derived_from gives a confsing result

Additionally, is there a perlapi that will say what it thinks the type of THIS is?

You can find out what ST(0) is with:

warn("ST(0) is of type %s\n", HvNAME(SvSTASH(SvRV(ST(0)))));
[download]

A demo:

use Inline C => Config =>
    BUILD_NOISY => 1;

use Inline C => <<'EOC';

void foo(SV * x) {
    dXSARGS;
    if (sv_isobject(ST(0)))
        warn("ST(0) is of type %s\n", HvNAME(SvSTASH(SvRV(ST(0)))));
    else warn("Not an object\n");
    XSRETURN(0);
}


EOC

use Math::BigInt;
my $obj = Math::BigInt->new(17);
foo($obj);
[download]

Cheers,
Rob

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Re^2: sv_derived_from gives a confsing result by geoffleach (Scribe) on Mar 29, 2011 at 05:08 UTC
Thanks, Rob. Your code, plus this: `warn("not an object %s\n",(char )SvPV_nolen(ST(0)));` [download] Revealed that ST(0) was '1', leading to the discovery that despite coding that looked* like C++, Perl was not treating it as such. Seems to be related to the fact that there was no new() method. Sigh!	[reply] [d/l]
Re^3: sv_derived_from gives a confsing result by ikegami (Patriarch) on Mar 29, 2011 at 08:52 UTC
`Audio::TagLib::ID3v2::Frame::size(1)` would be just as wrong in C++. The C++ equivalent of the correct code would be «`frame->size()`».	[reply] [d/l] [select]
Re^3: sv_derived_from gives a confsing result by syphilis (Archbishop) on Mar 29, 2011 at 10:43 UTC
Seems to be related to the fact that there was no new() method Sounds feasible. The method doesn't need to be called "new" (with C, at least), but if `sv_isobject(sv)` is to return true, then the reference (sv) does need to have been blessed into some package ... which is what "new" normally does, of course. Cheers, Rob	[reply] [d/l]