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Re: modules and C
From: |
Marco Maggi |
Subject: |
Re: modules and C |
Date: |
Fri, 23 Mar 2007 08:01:48 +0100 |
"David Fang" wrote:
> What do I need to do to export my scm_c_define_gsubr'd
> functions to the module?
YMMV. This is what I do:
1. write a C module with its own initialisation function,
let's say that the module's file is "module.c" :
/* C module */
#include <libguile.h>
/* module functions here */
void
my_module_init (void)
{
}
/* end of module */
put the init function in an internal header file:
void my_module_init (void);
2. wrap all the Scheme interface function declarations
into SCM_DEFINE: for a function with a prototype:
extern SCM my_scheme_func (SCM arg1, SCM arg2);
declared in a header file, I write in the body of the
module:
#undef SFN
#define SFN "my-scheme-func"
SCM_DEFINE(my_scheme_func, SFN,
2, 0, 0, (SCM arg1, SCM arg2), "")
{
SCM s_result;
/* do something with 'arg1' and 'arg2' */
return s_result;
}
the symbol SFN is defined to be the name of the
Scheme procedure: that way the name is available
in the function's body for calls to 'scm_error()',
for example:
/* to throw a 'wrong-type-arg' error */
if (error_condition)
scm_error(scm_arg_type_key, SFN,
"error message",
SCM_BOOL_F, SCM_BOOL_F);
3. in the body of the module initialisation function
put an include for a ".x" file:
void
my_module_init (void)
{
/* other init stuff */
#ifndef SCM_MAGIC_SNARFER
# include "module.x"
#endif
}
4. before compiling: preprocess the "module.c" file
with the Guile snarfer program; I use a rule in
the Makefile, something like this
.SECONDARY: %.x
GUILE_SNARF = guile-snarf
%.x : %.c
$(GUILE_SNARF) $(@) $(<) $(INCLUDES)
%.o : %.c $.x
the ".x" file holds the function invocations
required to define the functions from "module.c"
something like:
scm_c_define_gsubr(s_my_scheme_func, 2, 0, 0,
(SCM (*)()) my_scheme_func); ;
when the snarfer processes the file the:
#include "module.x"
is excluded, but it is included when the compiler
does its job;
now you can use 'scm_c_call_with_current_module()'
and invoke the initialisation function.
--
Marco Maggi