http://www.perlmonks.org?node_id=708995


in reply to Inline::C hash access

For the method shown here, I doubt it would make much difference, and if it did, it'd probably be to slow it down rather than speed it up. If you're going to write things in C to speed them up, then it helps to have the data in C structures and access it there. Otherwise you might as well just use perl instead of introducing additional access layers.

Still, I could be wrong since the slowest part of perl is calling a sub. If you called your C function the hundreds of thousands of times from the C code (rather than from perl), it could possibly speed it up.

UPDATE: also, I've completed my assignment. I hope I get an A on my homework. (In all seriousness, I've never tried Inline::C before. Normally I don't write complete solutions...)

BTW, the secret to figuring this stuff out is: you can't. It's really really arcane. But these pages can help: perlxs, perlapi, perlguts, perlxstut, perlclib, and perlcall. I used perlxs, perlapi, perlguts, and some source I had written before to figure this out. It can also help to browse the source of perl itself.

#!/usr/bin/perl use strict; use Inline 'C'; use Data::Dumper; my $hash = { parent => { parent => {} } }; root($hash); print "", Dumper({initial=>$hash, result=>root($hash)}), "\n"; __END__ __C__ SV* root(SV* sv) { if( SvOK(sv) && SvTYPE(sv) == SVt_RV ) { HV* h = SvRV(sv); SV* r; int i = 0; while( hv_exists(h, "parent", 6) ) { r = *( hv_fetch(h, "parent", 6, 0) ); if( SvOK(r) && SvTYPE(r) == SVt_RV ) { h = SvRV(r); i = 1; } } if( i ) { SvREFCNT_inc(r); return r; } } else { croak("please pass hash refs to root"); } return &PL_sv_undef; }

-Paul