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Re^4: Dynaloader/XS: sharing C symbols across shared objects

by creamygoodness (Curate)
on Jun 11, 2008 at 00:09 UTC ( #691361=note: print w/replies, xml ) Need Help??


in reply to Re^3: Dynaloader/XS: sharing C symbols across shared objects
in thread Dynaloader/XS: sharing C symbols across shared objects

Pointers to functions in C ? ... then wrapped in an SV ?

C function pointers are directly analogous to perl subroutine references. The big differences are...

  • They're typed, so function signatures must match.
  • The syntax for declaring them is bloody awful. In fact, it's so awful that many people use typedefs whenever possible.
  • You can't verify that a non-NULL function pointer actually points to anything valid, unlike in Perl where you can verify a sub ref with ref($sub).
Here's a demo for passing a function pointer around via SV.
use strict; use warnings; use Inline C => <<'END_C'; typedef void (*hello_func_t)(); void hola_mundo() { printf("Hola, mundo!\n"); } SV* get_hola_mundo_func_ptr() { return newSViv( PTR2IV(hola_mundo) ); } void do_hello(SV *sv_with_func_ptr) { IV temp = SvIV(sv_with_func_ptr); hello_func_t hello = INT2PTR(hello_func_t, temp); hello(); } END_C my $func_ptr = get_hola_mundo_func_ptr(); do_hello($func_ptr);
--
Marvin Humphrey
Rectangular Research ― http://www.rectangular.com

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