how to access subr from scm module?

how to access subr from scm module?

[Viktor Pavlenko]

Hi all,

I have the following situation:

1) a SCM procedure (*my-c-proc*) is defined in C and exported with
   scm_c_define_gsubr;
2) my program loads a SCM module (my-module.scm) by calling
   scm_c_use_module("my-module")
3) this module defines some SCM procedures I want to call from C code
4) these procedures will use *my-c-proc* mentioned in (1)

The problem is that *my-c-proc* is not visible in my-module and
scm_call_N will fail with

    ERROR: Unbound variable: *my-c-proc*

This procedure, however, is accessible from C since
scm_c_eval_string("*my-c-proc*") produces
#<primitive-procedure *my-c-proc*>.

I would prefer making a SCM module of my C procedures but they are
defined in the same code that wants to use them, so

    (define-module (my-c-procedures))
    (load-extension "??" "??")

doesn't seem useful. It would be OK though to load them as global
definitions, and scm_c_define_gsubr is supposed to do so according to
the docs:

     "Create a new subr object named NAME, based on the C function
     FUNCTION, make it visible to Scheme the value of as a global
     variable named NAME"

but that doesn't work for me. So what's the trick to make it work and
make it nice?

Thank you in advance.

Viktor


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Re: how to access subr from scm module?

[Viktor Pavlenko]

>>>>> "VP" == Viktor Pavlenko <vvp@rogers.com> writes:

    VP> I would prefer making a SCM module of my C procedures [...]

... and this is how to do it (I'm posting this in hope it may save
someone's time).

Regards
Viktor

------------------------------------------------------------------>8
#include <libguile.h>

SCM my_proc()
{
    return scm_makfrom0str( "testing" );
}

void
init( void* )
{
    SCM proc_scm = scm_c_define_gsubr( "*my-proc*", 0, 0, 0, my_proc );
    scm_c_export( "*my-proc*", 0 );
}

void
inner_main( void*, int argc, char **argv )
{
    scm_c_define_module( "test-module", init, 0 );

    /* using it from C */
    scm_c_use_module( "test-module" );
    scm_c_lookup( "*my-proc*" );  /* OK */

    /* to use it from a scheme module loaded from C code:
       (use-modules (test-module))
       (*my-proc*)
     */
}

int
main( int argc, char** argv )
{
    scm_boot_guile(argc, argv, inner_main, 0);
    return 0;
}
------------------------------------------------------------------>8


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